Atruck driver getting paid more than a school teacher is due to
a. glass ceiling in the job market
b. discrimination in the job market
c. compensating wage differentials
d. differences in human capital

C) Compensatig wage differentials

Explanation:

Driving a truck is not an easy job. It is uncomfortable, usually requires long-hours. Truck drivers frequently have to work at night, pull all-nighters. They are prone to health issues like backache, etc.

They have to be offered a higher wage for accepting that kind of job, and that is what compensating wage differentials are about: it consists in offering higher wages for unpleasant jobs, hence the adjective "compensating", it is a wage that compensates the unpleasantness.

corrupt also means cruel