Which of the Following Is Not Correct Concerning Structured Field

Which of the following is not correct concerning structured field interviews?

A) the researcher can change the order in which questions are asked
B) the researcher can use follow-up questions to clarify an earlier prepared question
C) the researcher must stick to the questions prepared prior to the interview
D) the researcher should ask questions in a manner that always keeps the subject on target and not wandering to areas of no interest to the researcher