问题啊，求答案，求解释

ssysyjzmf

Museums that house Renaissance oil paintings typically store them in environments that are carefully kept within narrow margins of temperature and humidity to inhibit any deterioration. Laboratory tests have shown that the kind of oil paint used in these paintings actually adjusts to climatic changes quite well. If, as some museum directors believe, paint is the most sensitive substance in these works, then by relaxing the standards for temperature and humidity control, museums can reduce energy costs without risking damage to these paintings. Museums would be rash to relax those standards, however, since results of preliminary tests indicate that gesso, a compound routinely used by Renaissance artists to help paint adhere to the canvas, is unable to withstand significant variations in humidity.
In the argument above, the two portions in boldface play which of the following roles?
A.    The first is an objection that has been raised against the position taken by the argument; the second is the position taken by the argument.
B.    The first is the position taken by the argument; the second is the position that the argument calls into question.
C.    The first is a judgment that has been offered in support of the position that the argument calls into question; the second is a circumstance on which that judgment is, in part based.
D.    The first is a judgment that has been offered in support of the position that the argument calls into question; the second is that position.
E.    The first is a claim that the argument calls into question; the second is the position taken by the argument.

jennychiu

答案是D

sasha_wen

哪里是boldface?