Which of the Following Statements About References Is True

Which of the following statements about references is true?

A) The most frequently contacted references are co-workers.
B) Never ask someone for permission to use him or her as a reference because this creates a bias.
C) Choose similar references, such as three professors or three co-workers.
D) Contacting references is a good way for an interviewer to validate his or her personal observations about an interviewee.
E) All of the above statements about references are true.