came across this question on internet.

Scientists have identified an asteroid, 2000 BF19, that is about half a mile wide and, if it strikes Earth, it can do tremendous damage to part of the planet but probably not cause planetwide destruction.
A. and, if it strikes Earth, it can do tremendous damage to part of the planet but
B. and, if it would strike Earth, part of the planet could experience a tremendous amount of damage but it would
C. and that, if it were to strike Earth, could do tremendous damage to part of the planet but would
D. and that, if Earth is struck by it, can do part of the planet tremendous damage, but it would
E. and that, if it strikes Earth, it could experience a tremendous amount of damage but


do we need that in the and to make to clauses parallel ?
what is wrong with B ? if it would & if it were aren't they parallel ?

Scientists have identified an asteroid, 2000 BF19, that is about half a mile wide and, if it strikes Earth, it can do tremendous damage to part of the planet but probably not cause planetwide destruction.

So ...2 things about the asteroid
1. that is about half a mile wide
2. that, if it were to strike Earth, could do tremendous damage to part of the planet

So , I would go in for C

I can understand why C has to be right.
But with options B,C and D the "would" at the end of the statement might create some redundancy when coupled with the word "probably" immediately after it.
I was initially hoping with the option "C". But Chose "A" as the redundancy was pretty evident.
Please help me out here!!
And also please help me out with the usage of "IT" about what it refers at various situations.

Dear Instructors,

I came across the same question in GMAT Prep. Correct OA is C. i am unable to identify the reasons behind the correct ans. I chose B during test.
Kindly confirm the reasons for the correct ans as C

Hi,

In my opinion, this sentence has two main issues. First is parallelism with "and" as the marker. Since the first clause before "and" starts with that, we need that after the second clause as well. On this rule, we can rule out choices A and B.

Second issue is with the second clause after "and". I think its a case of "if/then" constructions.

Choice A: Correct Usage: "If Present, Then Can"
Choice B: Incorrect usage of "would". "would" and "should" can never be used in the "If" part of the sentence.
Choice C: Correct Usage: "If Hypothetical Subjunctive, Then Conditional".
Choice D: Probably correct usage of "If/Then" (same as Choice A) however I think the sudden change to passive voice - "if Earth is struck by it" is not right. Also, rest of the sentence also seems a bit awkward.
Choice E: In this, I am not at all sure whether "could" is correct or not. According to the rule used in choice A, "can" would be a better candidate with present tense in the "if" part of the sentence. "could" goes better with hypothetical subjunctive. But whether it is grammatically incorrect, am not sure. Good thing is that this choice contains a pronoun ambiguity. "it could experience a tremendous amount of damage" seems to refer to the asteroid when it should refer to Earth.

So based on the above reasons, we can see that the answer is C. Now please do not take this as the correct reasons unless an instructor validates this post.

Thanks

Sunil

PS: For people who are not sure about the "If/Then" constructions, please refer to MGMAT SC Guide, chapter 7 on Verb Tense, Mood and Voice.

I think we can eliminate B, D and E because they have wrong if/then constrictions (absolutely agree with varun_783).
Btw A and C we should take C (with THAT) because if we remove sentence between commas in A the option will not make sense

Scientists have identified an asteroid, 2000 BF19, that is about half a mile wide and, if it strikes Earth, it can do tremendous damage to part of the planet but probably not cause planetwide destruction.

For me it has two flaws
(1) we need a comma before AND
(2) the sentence looks like IT CAN DO ... parallels to SCIENTISTS HAVE, the parallel which is wrong.

By the way, please move this thread to GMAT PREP

echo what varun said

prallelism and if+subjunctive construction are key. in fact the latter eluminates all the answer choices on its own.

other problems with the answer choices that may help eluminate wrong answers

a) pronoun it refers to earth. it must refer to asteroid. ambigious, therefore wrong.
b) planet experiencing damage = akward/unidiomatic
d) can do part of the plane tremendous damage = akward/unidiomatic.
e)planet experiencing damage = akward/unidiomatic

Hi,

To all who may want to understand this in simpler words (purely an opinion):

Answer choice C is correct : The use of due to the use of "were" -
Assume current space and time. When one wants to refer to the future, we use the word "were" eg: If i "were" Bill Gates, I would donate all my money.

If one goes back in time : eg: say one refers to a conversation between two gentlemen and writes : Karan told jacob that he "would" complete the job. Here "would" is used since the discussion took place before the job was completed, hence, in effect, would is used for events when talking about the future once in the past.

Hi karanrob,

I probably will not use that logic to solve this question. This deals with something called hypothetical subjunctive i.e. it deals with verb "mood".

It talks about a situation which is hypothetical in nature and that does not imply that it is in future tense. It simply talks about an imaginary situation.

Regards

Sunil

answer choice E inserted

Scientists have identified an asteroid, 2000 BF19, that is about half a mile wide and that, if it strikes Earth, it could experience a tremendous amount of damage but probably not cause planetwide destruction.

most likely the if/then is incorrect because it should be
if present -> can/may, not could. I had to look that up in the guide again

fortunately the second part is more obvious

an asteroid
that is about half a mile wide
and
that it could experience


first "that" is an essential modifier.

second "that" is trying to be a subordinate clause as evidenced by the subj/verb after it. I don't think the "IT" is ambiguous