A simple random sample of 1,240 adult Americans is selected, and each person is asked the following question: In light of candidate Jones’s alleged criminal activity do you believe he should withdraw from the race? 67% of those surveyed agreed that he should withdraw. Which of the following is an appropriate conclusion about the results?

a. They are inaccurate because of voluntary response.
b. They are inaccurate because of convenience sampling.
c. They probably understate the percentage of people who favor his withdrawal because of the question’s wording.
d. They probably overstate the percentage of people who favor his withdrawal because of the question’s wording.