IMO C

In cold-water habitats, certain invertebrates and fish convert starches into complex carbohydrates called glycerols, in effect manufacturing its own antifreeze.
(A) in effect manufacturing its own antifreeze --> its here is not suitable because the mentioned objects are vertebrates and fish, so can't be it
(B) effectively manufacturing antifreeze of its own --> the same error
(C) in effect manufacturing their own antifreeze --> in effect correctly plays the role of an adv, and them are better than it --> the best
(D) so that they manufacture their own antifreeze --> they here play the role of a subject of the new clause but it is not clearly modified for which Noun: carbonhydrates, glycerols, starches or vertebrates and fish ???. Finally, using clause here is more complex than using participle phrase as (A), (B) and (C)
(E) thus the manufacture of its own antifreeze --> wordy and wrong meaning, etc

In cold-water habitats, certain invertebrates and fish convert starches into complex carbohydrates called glycerols, in effect manufacturing its own antifreeze.

(A) in effect manufacturing its own antifreeze
(B) effectively manufacturing antifreeze of its own
(C) in effect manufacturing their own antifreeze.
(D) so that they manufacture their own antifreeze
(E) thus the manufacture of its own antifreeze

I can't understand the meaning of this sentence. My question is: Is "manufacturing ... antifreeze" the result of action "convert" done by invertebrates and fish? If so, then why don't we have structure: "Main clause, Verb-ing" to express the result of the main clause?
_________________

Yes you are right that conversion of starches leads to manufacturing of antifreeze.
But in GMAT we have to find the best option out of the 5 options presented to us. This does not mean that the correct option is the best available option in the whole world


Options A, B and E can be eliminated because of the usage of singular pronoun its with plural noun invertebrates and fish.

The only contenders are C and D.

The problem with D is that, they is ambiguous here. THEY might refer to invertebrates and fish or carbohydrates. Moreover (D) somehow changes the intended meaning of the sentence.

D says: Invertebrates do X so that they can cause Y.
Here focus is more on Y. Invertebrates are doing X just to achieve Y.

C says: Invertebrates do X, causing Y.
So here Y implicitly gets done when Invertebrates do X.
This is the intended meaning.

Note: This question has already been discussed in the following thread:
in-cold-water-habitats-certain-invertebrates-and-fish-76847.html

Please search properly before posting a new question.

'certain invertebrates and fish' is a plural noun and hence requires plural verb 'their'. A, B and E are out.

(C) in effect manufacturing their own antifreeze. Correct option as it mentions the intended meaning.

(D) so that they manufacture their own antifreeze. 'So that' depicts that something is done intentionally by the organisms, but this is not the case. Something is done without any intentions. Hence this is a wrong choice
_________________

We have 3:2 split here. 'Its' is not the correct pronoun to be used here. Eliminate A, B and E

Between C and D:
(C) in effect manufacturing their own antifreeze - Correct. Correctly modifies the action described in the previous clause

(D) so that they manufacture their own antifreeze - Incorrect. Meaning error. This option suggests that the invertebrates and fish intentionally converted starch to carbohydrates to manufacture their own antifreeze.

Answer: C

Meaning : In cold water habitats, some invertebrates and fish convert starches into glycerols to protect themselves from freezing.

Mistake analysis : invertebrates and fish are plural so there has to be plural pronoun. So, A,B and C are eliminated.

D) so that indicates purpose or in order that, so here for the conversion purpose they manufacture their own antifreeze is wrong.

It is due to the cold effect they manufacture their own antifreeze.

So Option C is correct.

A, B, and E are out - SVA error

its -- invertebrates and fish

C - corrects that SVA
D - changes the meaning (D sounds like converting starches enables them to make antifreeze,
While the intended meaning is converted starches is their antifreeze)

Hi
"D" seemed correct answer to me, but I understand that D is actually changes the meaning.

However I am still confused how answer choice C is grammatically correct?
"in effect manufacturing their own antifreeze" is it prepositional phrase? Or present participial?
Someone in the above explained that "in effect" is adverb, in that case which word, phrase or clause "in effect" modifys?

I guess I have some grammatical gap

Posted from my mobile device

Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________