(A) Incorrect . For the errors mentioned above.
(B) Incorrect . For the following reasons:
- Error no. 1 of the original sentence.
- "would crystallize" and "was growing" are not parallel, even though they need to depict parallel actions
- Error no. 3 of the original sentence
(C) Incorrect . For the following reasons:
- The use of past perfect "had raised" is incorrect given that past progressive "were exhaling" has been used. The use of past perfect indicates that the moisture had raised the humidity levels even before the moisture was exhaled by the tourists!
- Error no. 2 of option B
(D) Incorrect . For the following reasons:
- "fungus was growing" in the non-underlined part is not parallel to anything before "and".
- The structure "because of moisture raising_" is an indirect and confusing way to communicate the same idea expressed very clearly in option E.
(E) Correct . The sentence correctly uses past perfect "had raised" to communicate that the humidity had been raised before the chambers were closed. Even though the reference for ?them? is ambiguous ? it could refer to either "tourists" or "chambers" ? pronoun ambiguity is not a deterministic error on GMAT, as this question clearly demonstrates.
Also, please pay good attention that the way the idea is communicated in this option makes the meaning so much clearer than the meaning in any other option. All other options were presenting "moisture" as the reason for the closing down of the chambers and then were providing additional information about the moisture. However, this option very clearly expresses that the reason is that the moisture had raised the humidity levels within the chambers. Please take time to understand this difference in clarity because I have seen such differences in many other official questions too. Such understanding may help you in identifying correct choices in the future. For example: Look at the below sentences and see which sentence communicates the idea more clearly.
- The meeting was cancelled because of the president who did not arrive on time.
- The meeting was cancelled because the president did not arrive on time.
The second one is clearer. Right?