Sentence Correction

In late 1997, the chambers inside the pyramid of the Pharaoh Menkaure at Giza were closed to visitors for cleaning and repair due to moisture exhaled by tourists, which raised its humidity to such levels so that salt from the stone was crystallizing and fungus was growing on the walls.
(A) due to moisture exhaled by tourists, which raised its humidity to such levels so that salt from the stone was crystallizing
(B) due to moisture that tourists had exhaled, thereby raising its humidity to such levels that salt from the stone would crystallize
(C) because tourists were exhaling moisture, which had raised the humidity within them to levels such that salt from the stone would crystallize
(D) because of moisture that was exhaled by tourists raising the humidity within them to levels so high as to make the salt from the stone crystallize
(E) because moisture exhaled by tourists had raised the humidity within them to such levels that salt from the stone was crystallizing

[spoiler]I got the question right with the parallelism rule here, but I have doubt with the pronoun reference used here. The OG says 'them' in C and D is wrong while it is correct in E. How is it so ? Can anyone explain ?[/spoiler]

This is an example of a question where it is better to arrive at the correct answer choice by eliminating other mistakes not related to the controversial pronoun. Pronoun ambiguity is the subject with reference to which the GMAT does not demonstrate one clear stand.

sam2304 wrote:In late 1997, the chambers inside the pyramid of the Pharaoh Menkaure at Giza were closed to visitors for cleaning and repair due to moisture exhaled by tourists, which raised its humidity to such levels so that salt from the stone was crystallizing and fungus was growing on the walls.
(A) due to moisture exhaled by tourists, which raised its humidity to such levels so that salt from the stone was crystallizing
(B) due to moisture that tourists had exhaled, thereby raising its humidity to such levels that salt from the stone would crystallize
(C) because tourists were exhaling moisture, which had raised the humidity within them to levels such that salt from the stone would crystallize
(D) because of moisture that was exhaled by tourists raising the humidity within them to levels so high as to make the salt from the stone crystallize
(E) because moisture exhaled by tourists had raised the humidity within them to such levels that salt from the stone was crystallizing

[spoiler]I got the question right with the parallelism rule here, but I have doubt with the pronoun reference used here. The OG says 'them' in C and D is wrong while it is correct in E. How is it so ? Can anyone explain ?[/spoiler]

is the answer E?

I think here structure of the sentence decides whether pronoun is correct or not, If two sentences are structurally parallel (subject, Object and verb) then subject and verb can be replaced with pronouns. See the difference between D and E.

Raising the Humidity between them
Had raised the humidity between them

7777 wrote: is the answer E?

Yes. OA : E