Grockit - Which and That Issue

[akashkumar1987]

Poikilotherms can subsist in what would be fatally food-depleted environments; they expend over 70% less energy than homeotherms per pound of body weight which allowed them to survive on far less food.

A - weight which allowed
B - weight, which allows
C - weight which has allowed
D - weight that has been allowing
E - weight allowing

Answer - B

Please let me know why it is the correct answer[/u]

[Kasia@EconomistGMAT]

The sentence compares poikilotherms with homeotherms and it speaks about general differences between them. The sentence does not include any time reference - therefore, we can assume the statement is general and speaks about facts that are ALWAYS TRUE. Thus the sentence should use the Present Simple tense. Based on that, we can eliminate all answers but B.

[gmat6087]

The sentence compares poikilotherms with homeotherms and it speaks about general differences between them. The sentence does not include any time reference - therefore, we can assume the statement is general and speaks about facts that are ALWAYS TRUE. Thus the sentence should use the Present Simple tense. Based on that, we can eliminate all answers but B.

what is wrong in (e) ? can you please explain

[Kasia@EconomistGMAT]

The word "allowing" modifies "weight" and, therefore, answer E changes the meaning of the original sentence. It is the fact that poikilotherms expend over 70% less energy than homeotherms do that allows them to survive and NOT simply their WEIGHT.

[gmatdriller]

Choice B, inserted:

Poikilotherms can subsist in what would be fatally food-depleted environments; they expend over 70% less energy than homeotherms per pound of body weight, which allows them to survive on far less food.

The word "allowing" modifies "weight" and, therefore, answer E changes the meaning of the original sentence. It is the fact that poikilotherms expend over 70% less energy than homeotherms do that allows them to survive and NOT simply their WEIGHT.

A general idea was stated in the preceding clause and we are told that the consequence (or logic) follows that Poikilotherms are able to survive on far less food than do homeotherms.
This appears like a rare case where "WHICH" is modifying an entire clause (presenting a result of the preceding clause). Is this one of the function of "WHICH", or is something wrong with the question?

[Kasia@EconomistGMAT]

"Which" should not refer to the first clause. A clause that follows "which" can modify only the clause placed directly before it, i.e. "they expend over 70% less energy than homeotherms per pound of body weight."
The question is a bit strangely phrased. It is better to stick to the official problems.