Regarding the Stages of and Procedures for Conducting a Survey

Regarding the stages of and procedures for conducting a survey,

A) computer-assisted interviewing eliminates the need for pretesting the survey instrument.
B) follow-up efforts are especially important in mail surveys.
C) supervision and quality control are most difficult in a telephone survey.
D) in personal interview surveys, interviewer training generally focuses on teaching interviewers how to detect whether respondents are telling the truth.