[单项选择]

Personal interviewing is most effective when all the people to be interviewed are located in a relatively small geographical area. Otherwise, the time and expense spent in travelling from one person to another makes this type of interviewing economically impractical. Personal inter viewing is usually used when the information needed is too complex to be gathered by another technique. For example, a problem being studied may require the interviewer to probe beyond the more superficial answers that might be obtained with another method.
It is sometimes assumed that personal interviewing is the most accurate of all survey re search techniques. Although personal interviewing may be accurate in many cases, human errors may prevent a researcher from obtaining valid results. Questions perceived by the interview wee as an invasion of privacy or threatening in any way will probably produce false of partially true answers. Also, since the interviewer must interpret the respo
A. the interviewer can ask the interviewee questions again in different ways
B. the interviewer can ask the interviewee some personal questions
C. the initial question do not produce the information desired
D. no one is present to clarify questions