A community college mathematics department chair, Prof. Arrow, is looking at applications for its mathematics instructor positions. Prof. Arrow, whose research interests are practical applications of mathematics, is sure to reject highly qualified applicants who specialize in differential equations even when these applicants would have served the student body and college well. This is an example of

a$.$ price discrimination.

b$.$ a principal$-$agent problem.

c$.$ a whistleblower.

d$.$ an oral auction.