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.
(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
becasue of 后面其实就一个N:mositure。后面一大块全是一个从句。 这里的从句是和M一层的。所以这里的them指代T
(E) because moisture exhaled by tourists had raised the humidity within them to such levels that salt from the stone was crystallizing