Which of the Following Factors Is Extremely Important to Evaluating

Which of the following factors is extremely important to evaluating public opinion through surveys?

A) People interviewed must be representative of the entire population.
B) Asking questions of only those people who have a real stake in the political system.
C) Survey responses that do not follow popular opinions are to be thrown out of consideration.
D) The more people surveyed leads to more reliable assessments of public concerns.
E) Asking the same questions to the same people again and again to ensure that they understand the question.