The answer is, "This is principally used to exhibit changes in data over time." The question is,

U.S. industries like steel, computers, and energy need to be protected from foreign competition to ensure which of the following?

(A) The protection of these industries as they develop. (B) The presence of these industries during a crisis. (C) The incentive for these industries to become more efficient. (D) The economic advantages caused by their production.

Marginal revenue product is defined as the amount that an additional unit of the variable input adds to ____

a. marginal revenue b. total output c. total revenue d. marginal product e. none of the above