Regarding Client Approval of a Questionnaire

Regarding client approval of a questionnaire:

A) it serves to let the client understand the technical aspects of the research.
B) it serves as a check that the researcher is still in tune with the survey's objectives.
C) when signed by the client,it means that the questionnaire should not be changed for any reason,even if it performs poorly in the pretest.
D) client approval of the questionnaire is carried out at the original signing of the agreement to conduct research but it merely gives the researcher approval to use a questionnaire as clients should not be involved in approving the final questionnaire developed by expert researchers.
E) client approval is merely a legal requirement,and researchers do not encourage clients to review a questionnaire prior to its approval.