Can anyone explain in deep this question? I chose C but is incorrect. The OA is D. Thanks!

Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles islands.

A. sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of
B. sloth, that they found in Puerto Rico in 1991, has been dated at 34 million years old, thus making it the earliest mammal known on
C. sloth that was found in Puerto Rico in 1991, was dated at 34 million years old, making this the earliest known mammal of
D. sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on
E. sloth which, found in Puerto Rico in 1991, was dated at 34 million years old, made the sloth the earliest known mammal of

Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles islands.

A. sloth < modifier> found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of
B. sloth, that they found in Puerto Rico in 1991, has<singular> been dated at 34 million years old, thus making it the earliest mammal known on
C. sloth that was found in Puerto Rico in 1991, was <singular>dated at 34 million years old, making this the earliest known mammal of
D. sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on
E. sloth which, found in Puerto Rico in 1991, was <singular> dated at 34 million years old, made the sloth the earliest known mammal of

Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles islands.

> The subject of the sentence is 'Fossils'.

A. sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of
> 'it' can refer to 'arm' or 'sloth'
> This sentence without the modifiers means
'Fossils made sloth the earliest known mammal...'

B. sloth, that they found in Puerto Rico in 1991, has been dated at 34 million years old, thus making it the earliest mammal known on
> 'They' does not have an antecedent

C. sloth that was found in Puerto Rico in 1991, was dated at 34 million years old, making this the earliest known mammal of
> Fossils of the arm of a sloth that was found in Puerto Rico in 1991
> means that 'the sloth was found in Puerto Rico in 1991',

D. sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on
> correct

E. sloth which, found in Puerto Rico in 1991, was dated at 34 million years old, made the sloth the earliest known mammal of
> incorrect construction. can be readily eliminated.

Thanks, I understand.
I suppose that E is wrong because of the "which". Is it correct?

if you eliminate the intervening modifier, you get "the sloth, which ... was dated at 34m years old".

this is wrong. it's not the sloth that has been dated at that age, it's the fossils.

so yes, this "which" modifier is incorrect.

Ron... is 'dated at' a correct idiom? (vs dated to be)

Dated to be is not idiomatic.
Check the last SC Q of OG 12
"Rock samples taken from the remains of an asteroid
about twice the size of the 6-mile-wide asteroid that
eradicated the dinosaurs has been dated to be 3.47
billion years old and thus is evidence of the earliest
known asteroid impact on Earth."

_________________
Many of the great achievements of the world were accomplished by tired and discouraged men who kept on working.

this is a question to which you already know the answer, since this is an official problem whose correct answer contains "dated at".

DO NOT QUESTION CORRECT ANSWERS TO OFFICIAL PROBLEMS.

ANYTHING THAT APPEARS IN A CORRECT ANSWER TO AN OFFICIAL PROBLEM MUST BE CONSIDERED ACCEPTABLE.

Hi ,

can anyone explain why 'have been dated ' is correct?? I understand that since fossils are plural , the plural form have should be used but why the past perfect form ??

Thanks
tinku

Hi Ron/Stacey,

In the option d , why 'have been dated' is correct ?

It sounds good to me, but why present perfect tense is used in this case.

in describing a past event that is no longer occurring, we can use either the present perfect or the simple past. the difference between the two is one of semantic meaning:

* the present perfect (has/have VERBed) is used if the event still has a tangible impact or influence on, or relevance to, the present state of affairs.

* the simple past is used if the event does NOT have any tangible impact/influence/relevance in the present.

note that, in many cases, either of these tenses could be used to describe exactly the same event in exactly the same timeframe!
here's an example: imagine that you are talking to a guy, at a bar, who has had 3 marriages. (he is currently divorced.)

if the two of you are actually talking about marriage, he will probably say "i have been married three times".

if the two of you are NOT directly talking about marriage or its consequences -- for instance, he is just enumerating members of his family -- he will probably say "i was married three times".

both of these are correct -- in terms of both grammar and semantics.

--

in the example at hand, the present perfect probably makes a little bit more sense, since the findings clearly have direct relevance to the situation being discussed at present. however, it would certainly not be incorrect to use the simple past (although that usage would suggest that the findings no longer have relevance, possibly because they have been superseded by some more recent findings).

--

here are some words that i wrote on another thread, but which are also appropriate here:

Ron - is the usage of AND incorrect in A)

Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 millions year old"

the ", and" make it look like an independent clause but it isn't, should it be just "and " .

I'm having a tough figuring about when to " , and " vs " and ".
Much thanks

that's one way of eliminating that choice, although you have to be VERY careful in making that judgment -- it's quite possible to have a comma in front of “and” in a construction that's not an independent clause, if that comma belongs to some other construction (such as a modifier).

for instance:
i bought bananas and grapes --> normal parallel structure; there shouldn't be a comma here.
i bought bananas, which were on sale, and grapes. --> here there is a comma in front of “and”, but that comma belongs to the green modifier.

--

what's probably an easier way to eliminate the same choice is to realize that you can't block off a modifier with a comma on only one side. modifiers should be blocked off either with commas on both sides (nonessential modifiers) or with commas on neither side (essential modifiers).
in that choice, "found in Puerto Rico in 1991" is blocked off with a comma on the right, but not on the left. bad news.

Thanks Ron super clear on that now, and great point on the modifier.

sure thing