Because of the relationship between a perfectly competitive firm's demand curve and its marginal revenue curve, the profit maximization condition for the firm can be written as

Refer to the graph below. The slope of the line tangent to the curve at point A is:

A. 0
B. .5
C. 2
D. 4

Two workers are employed in the same job by the same firm; however, they are paid different wage rates. This could be explained by differences in

a. the price of the firm's output b. their marginal products due to differences in ability c. working conditions d. the income effect e. risk