Interview Surveys Have a Number of Advantages Over Mail Surveys;which

Multiple Choice

Interview surveys have a number of advantages over mail surveys;which of the following is NOT one of those advantages?

A) Higher response rates
B) There is generally a smaller number of "don't knows" and "no answers"
C) There is a smaller number of relevant responses given
D) Observations can be made
E) All of these choices are advantages of the interview