The concept "planning and control unit" can be defined as
a. the division of the total market area of the firm into geographic areas with an equal number of accounts.
b. the division of the total market area of the firm into geographic areas containing the same approximate square miles.
c. the division of the total market area of the firm into geographic areas with an equal number of road miles.
d. some entity smaller than a territory into which the total market area of the firm is divided.
e. the division of the total market area of the firm into geographic areas called territories.
Answer: D