Figure 18-1 on the Graph, L Represents the Quantity of Labor and Labor

Multiple Choice

Figure 18-1
On the graph, L represents the quantity of labor and Q represents the quantity of output per week.
-Refer to Figure 18-1. Suppose the firm sells its output for $10 per unit, and it pays each of its workers $400 per week. When the number of workers increases from 4 to 5, the

A) marginal revenue is $450 per unit of output, and the marginal cost is $400 per unit of output.
B) value of the marginal product of labor is $3,900, and the marginal cost per unit of output is $400.
C) value of the marginal product of labor is $450, and the marginal cost per unit of output is about $8.89.
D) firm's profit increases.