To Assess the Opinion of Students at the Ohio State

To assess the opinion of students at The Ohio State University about campus safety, a reporter for the student newspaper interviews 15 students that she meets walking on the campus late at night who are willing to give their opinion. The sample obtained is:

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