Slaves were expensive factors of production in comparison to free labor. Which of the following was not a cost to slave labor?

In the economic way of thinking,

A) buyers compete against other buyers, sellers cooperate with other sellers, and buyers cooperate with sellers. B) buyers cooperate with other buyers, sellers cooperate with other sellers, and buyers compete with sellers. C) buyers compete against other buyers, sellers compete against other sellers, and buyers cooperate with sellers. D) buyers cooperate with other buyers, sellers cooperate with other sellers, and buyers cooperate with sellers.

The equation GDP = C + I + G + NX best describes the

a. the output approach to measuring GDP b. the factor payments approach to measuring GDP c. the value added approach to measuring GDP d. the expenditures approach to measuring GDP e. the exchanges approach to measuring GDP