GMAT Sentence Correction (SC) | Re: In late 1997, the chambers inside the pyramid of the Pharaoh

I assume that there's no question that option E is the correct answer. Now the question to what "them" is referring is more logical than grammatical? Here's my take -

In late 1997, the chambers inside the pyramid of the Pharaoh Menkaure at Giza were closed to visitors for cleaning and repair because moisture exhaled by tourists had raised the humidity within them to such levels that salt from the stone was crystallizing.

option 1 - In late 1997, the chambers inside the pyramid of
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