Scenario 13-3 Suppose a Certain Competitive Firm Is Producing Q=500 Units of Units

Scenario 13-3
Suppose a certain competitive firm is producing Q=500 units of output.The marginal cost of the 500th unit is $17,and the average total cost of producing 500 units is $12.The firm sells its output for $20.
-Refer to Scenario 13-3.At Q=500,the firm's profits equal

A) $1,000.
B) $4,000.
C) $7,000.
D) $10,000.