Answer:
The correct answer is d) The free-rider problem .
Explanation:
This term refers to a problem in economics where a person who is known as a stowaway, benefits from using a service or consuming a product without paying anything for it. In this case Kevin should contribute to the radio station, since regardless of whether what was expected in a given period has been raised, just being committed is enough to have the obligation to contribute for the maintenance of the station over time.