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

The OA is E
The explanation given in the OG is that the Pronoun "Them" refers to Tourists clearly in the option. Why do we remove D then? Both of the sentences have them far from what it is referring to -"Tourists"