What Are Two Primary Disadvantages of Mail Questionnaires

Multiple Choice

What are two primary disadvantages of mail questionnaires?

A) The mailing costs are high, and the response rate is low.
B) The response rate may be low, and the respondents may not be representative of the population.
C) The mailing costs are high, and the validity may decrease because of the survey's anonymity.
D) Completing the questionnaire may be inconvenient, and respondents may not be representative of the population.
E) An interviewer is usually present to bias the responses, and respondents may not be totally honest.