C
The appropriateness of the auditor's question depends on what he does with the information.
If he is trying to find out whether the client took steps to "determine ... the work environment needed to achieve conformity," his action is appropriate.
If he is going to raise a nonconformity based on his own opinion about the proper work environment, he is out of bounds. It is not up to the auditor to determine the correct work environment.
He is out of bounds also if he issues an observation or OFI, because he is consulting.
If he is trying to find out whether the client took steps to "determine ... the work environment needed to achieve conformity," his action is appropriate.
If he is going to raise a nonconformity based on his own opinion about the proper work environment, he is out of bounds. It is not up to the auditor to determine the correct work environment.
He is out of bounds also if he issues an observation or OFI, because he is consulting.
until you threw in "operator comfort".