if a firm in perfect competition earns zero

profits,

A. total revenue isequalto

total variable cost.

B.the price isequalto

average total cost.

C. the price isequalto

marginal cost.

D. the price isgreaterthan

marginal cost.

The supply curve of a firm in perfect competition is

A. its average total cost curve.

B. its marginal cost curve.

C. the same as its TC

curve.

D. its marginal revenue curve.