Refer to the Following

Multiple Choice

Refer to the following:
The following graph shows the marginal and average product curves for labor, the firm's only variable input. The monthly wage for labor is $2,800. Fixed cost is $160,000.

-When the firm uses 40 units of labor, how much output does it produce?

A) 1,600 units
B) 400 units
C) 4,000 units
D) 2,800 units
E) none of the above