The OA is provided in the initial post.
It is B.
Let's simplify the sentence to make it easier to evaluate:"
Animals have developed mechanisms which keep temperatures low."
Because the statement states a general rule, true regardless of time, the present tense is preferred to any other tense. Eliminate D (past tense).
"
to keep" and "
in order to keep" mean exactly the same thing. They are preferable to "
which keep" and "
that keep" because they better express the relationship between ideas: the mechanisms were developed with the purpose or objective of keeping temperatures low. "
In order to" expresses this idea whereas "
which" and "
that" do not provide any meaningful link between ideas. Eliminate A and D.
B is better than E only because B is more concise. They say the same thing.
B is correct.
Sometimes on the GMAT, you will run into a split like this; you will have to decide whether to use "to" or an alternative (here it is 'which/that'; typically it is 'and'). For instance consider the sentences below:
Sentence 1:
I went to the hospital and saw the doctor.
Sentence 2:
I went to the hospital to see the doctor.
If seeing the doc is the reason I went to the hospital, then the 2nd sentence is better than the first because it accurately describes the relationship between ideas. It demonstrates that I went in order to see the doctor. With the purpose or objective of seeing the doctor. If the author means to express intent, purpose, objective... then "
in order to" is appropriate. "
to" in this context is a contraction of "
in order to". Below is a final example.
Sentence 3:
Throughout the night, the soldiers dug trenches that would protect them from the invading army.
Sentence 4:
Throughout the night, the soldiers dug trenches to protect themselves from the invading army.
Sentence 4 is better, assuming that the trenches were dug specifically with the objective/purpose of providing protection.
Of course, "in order to" is not always right. Consider the sentences below:
Sentence 5:
After suffering a flat tire, John put in a new wheel and left the old one on the side of the road
Sentence 6:
After suffering a flat tire, John put in a new wheel to leave the old one on the side of the road
In this case, it does not make sense to argue that John put in the new wheel simply with the purpose/objective of leaving the other one on the side of the road. He put in the new wheel because he wanted to replace a flat tire. The relationship between the last two ideas is not
action to meet an objective, so it would be incorrect to use "in order to" or its contraction, "to". Thus sentence 5 is better than sentence 6.
If you have trouble picking the right answer when your are presented with several grammatically right choices, run drills in the
Drill Generator and select topic='SC Meaning' to help build your ability to recognize meaning errors.
Hope that helps,
-Patrick
