Why Did Carrington Choose to Interview Partners in Separate, Back-To-Back

Why did Carrington choose to interview partners in separate, back-to-back interviews instead of in joint interviews?

A) Carrington had too many questions to ask in one interview so divided the questions between partners and asked each partner half of the questions during their interview.
B) Back-to-back interviews allowed Carrington to manipulate aspects of the protocol so that respondents would turn on each other.
C) Joint interviews are difficult to schedule and Carrington revealed that he struggled to find times that would work for both partners.
D) Back-to-back interviews tend to reveal discrepancies in answers to the most routine questions about domesticity, thus revealing reality more than joint interviews.