A.The equality between marginal revenue and marginal cost is both a necessary and a sufficient condition for profit maximization.

-true

-False

B. A competitive firm decides to shut down its production when its average variable costs are greater than the market price.

-True

-False

C. A firm's short-run supply curve is derived from its marginal cost curve.

-true

-false

D. A firm's short-run supply curve becomes upward-sloping as soon as the firm does not decide to shut down its production.

-true

-false