87. While they remove carbon dioxide from the air, conserve soil and water, and house thousands of species, forests also supply potentially valuable pharmaceuticals, and, as sources of building material and firewood, that provide employment for millions worldwide.
A. pharmaceuticals, and, as sources of building material and firewood, that provide
B. pharmaceuticals, and sources of building material and firewood, are providers of
C. pharmaceuticals and, as sources of building material and firewood that are provide
D. pharmaceuticals and as sources of building material and firewood, for providing
E. pharmaceuticals and, as sources of building material and firewood, provide

This is GMATPREP question.I choose B. But this is not the OA. Pls can you help narrow down the correct answer. Also what are the errors in the wrong answers?

It's E.

ok, i call shens on this one - gmatprep problems aren't numbered.

what's the real source of this problem?

this problem is from GMATPREP test only. Some one has collected all these GMATPREP problem in a central document and numbered them. I am attaching a snapshot from my GMATPREP test to provide you reference that this problem was indeed from my GMATPREP test and I saved the snapshot since I did this question wrong. Link>>

Also some time GMATPREP repeats questions from the official guide thats the reason few questions posted from GMATPREP source looked like posted from official guide.

Thanks for all help in explanation.

ok, you win. :)
we have to be cautious here, you know.

--

first off, you can completely ignore all words coming before the word 'forests'. all the words before that point are a separate subordinate clause that doesn't at all affect the grammar in the following sentence (which stands perfectly well on its own).

with that said, let's look at the answer choices.

choice a:
sentence fragment.
two halves are coupled by the word 'and'. the first half (forests also supply valuable pharmaceuticals) has a genuine verb (supply), but the second half doesn't: it consists entirely of a long modifier (...as sources of building material and firewood, that provide...) and doesn't have a main verb. in other words, at the end of the sentence, you're left standing out in the rain, wondering exactly what it is that the sources that provide blah blah blah are doing.

choice b:
at least 3 things wrong.
- the wording seems to state that the forests supply pharmaceuticals but also supply 'sources of...'. that isn't right - they are sources of those things.
- there's no conjuction correcting the two clauses (forests supply... and are providers...) -- that 'and' isn't there
- 'are providers of' is wordy and much worse than just 'provide'

choice c:
- sentence fragment (there's no verb in the second half)
as sources of building material and firewood that are providing employment, they do what exactly? we don't know.

choice d:
- no comma after 'and', so sets up the expectation of parallelism. clearly there is no parallelism between 'supply potentially valuable pharmaceuticals' and 'as sources of building material and firewood', so that expectation is violated.
- 'for providing' makes no sense.

choice e: CORRECT
- parallelism works: 'supply ... ' is parallel to 'provide'
- the modifier (as sources of building material and firewood) is correctly set off by commas so that it doesn't interfere with the parallelism of the rest of the sentence.

Dear Moderators,

Would like to check the error in Option A.

For A, the answer has a comma before “and”, thus the sentence that follows must be an independent clause with a subject and a verb. For A, it only has a verb (provide).

Am I right?

KH

no, that's not the issue, because if that were an error, then choice e (the correct answer) would be wrong as well.

'and' can be a coordinating conjunction, as you assume it is here, but it can also serve merely to link two or more parallel items in a list. that's all 'and' is doing here: it joins together the two verbs that go with the subject 'forests'.

choice a is wrong because 'that' has no antecedent. if you take out the modifier set off by commas, you have the following:
forests ... supply potentially valuable pharmaceuticals, and that provide employment...
you should be able to see that 'that' makes no sense here.

Hi,

While they remove carbon dioxide from the air, conserve soil and water, and house thousands of species, forests also supply potentially valuable pharmaceuticals, and, as sources of building material and firewood, that provide employment for millions worldwide.


In this question why doen'nt "While they remove carbon dioxide from the air" not modfiy conserve soil and water... It does not affect anything out here and it obviously does not make sense that conserve soil and forest could remove carbon dioxide from the air.. But my point is i always take modifers to modify the closet available noun or word for that matter...

There is a similar construction in OG 10 which reads as "Initiated on Columbus Day 1992, five centuries after Europeans arrived in the New World, Project SETI.... In this case the OG is taking Initiated to modify Project SETI and not Five centuries.. Please comment ... I have not posted the full question from OG as it is banned


Thanks

this merits both a specific response and a general response.

specific response:
1) first of all, it can't modify "conserve soil and water", because it can only modify nouns (or things that act as nouns do, such as noun phrases or pronouns). in fact, such modifiers must modify nouns that begin independent clauses - i.e., the subject of the clause that follows.
more importantly,
2) the parallelism of the verbs (remove carbon dioxide from the air, conserve soil and water, and house thousands of species) should be striking. because of that parallelism, it's clear that the entire series of 3 verb phrases must be part of the same modifier (because parallel structures aren't split into different grammatical functions).
if you didn't IMMEDIATELY recognize the parallelism of the 3 verbs in that construction - and it seems you didn't - then you need to work on recognizing parallelism! if i were to vote for one topic as the single most important for SC success, i'd vote for parallelism (although all the other topics are of course important as well).

general response:
it a modifier WORKS in one way, and DOESN'T WORK in another way, then the modifier should of course be interpreted in the way that works.




sure.

in this case, "five centuries ... World" is an appositive whose function is merely to modify / provide more information about "columbus day 1992". it can be disposed of without any changes to the grammar of the remainder of the sentence.

furthermore, the modifier is not allowed to modify "five centuries..." anyway, because "five centuries..." is not the noun starting an independent clause (as stated above).