Which method is likely to be used by a journalism student who is casually surveying opinions of students about the university's cafeteria food for an article that she is writing?

i believe the answer is: Convenience sampling

Convenience sampling refers to a method of sampling in which subjects are taken through the convenience of the researchers, either it's the people that are in close approximity with the researchers, the people that the researchers are already familiar with, or even the subjects that directly provided by the organization.