Which Is NOT an Example of a Principal-Agent Problem

Which is NOT an example of a principal-agent problem?

A) A union president makes a move to expand membership and strengthen his support,even though it compromises representation of current members.
B) Gwendolyn is visiting an unfamiliar city and takes a taxi to travel between destinations.The cab driver takes inefficient routes in order to increase her fare.
C) A U.S.representative gets legislation passed in order to fund a road project in her home district,despite opposition from nearly half of her colleagues.
D) Employees at a restaurant loaf around when the manager leaves for a few hours to purchase supplies.
E) An instructor carelessly grades an important exam in order to have more free time on the weekend.