A Small College Employs Two Economists

A small college employs two economists.Rob has been employed by the college for 15 years, and Nasrin has been employed for one year.Rob's salary is significantly higher than Nasrin's, despite the fact that he and she both have their doctoral degrees in economics.Each professor averages one publication per year, and both are excellent teachers.Given this information, the wage difference is best explained by:

A) compensating differentials.
B) differences in human capital.
C) discrimination.
D) differences in talent.