In a perfectly competitive industry the market price is $25. A firm is currently producing 10,000 units of output; average total cost is $28, marginal cost is $20, and average variable cost is $20. The firm should:

a. raise price because the firm is losing money.

b. keep output the same because the firm is producing at minimum average variable cost.

c. produce more because the next unit of output increases profit by $5.

d. produce less because the next unit of output decreased profit by $3.

e. shut down because the firm is losing money.

Indicate which answer is correct with a step-by-step explanation.