Traditionally, the Chief Difference Between an Agent and a Servant

Traditionally, the chief difference between an agent and a servant (employee) was that the:

A) servant was generally not employed to represent a principal in business dealings
B) servant was usually allowed more personal discretion in deciding how to accomplish a certain objective
C) agent was not controlled by the principal
D) servant acted on behalf of the master in contractual matters involving third parties
E) none of the other choices