In order to assess the opinion of students at the Ohio State University on campus safety, a reporter for the student newspaper interviews 15 students he meets walking on the campus late at night who are willing to give their opinion.

(a) The sample is

A. all students at universities with safety issues.
B. the 15 students interviewed.
C. all those students walking on campus late at night.
D. all students approached by the reporter.

(b) The sample obtained is

A. a simple random sample of students feeling safe.
B. a probability sample of students with night classes.
C. a stratified random sample of students feeling safe.
D. probably biased.

(c) The method of sampling used is

A. a census.
B. simple random sampling.
C. the Gallup Poll.
D. voluntary response.