Suppose That a Profit-Maximizing Monopolist Has a Plant of the Optimal

Suppose that a profit-maximizing monopolist has a plant of the optimal size and is producing a level of output at which price is $30, average total cost is $55, and average fixed cost is $40. The firm should

A) operate in the short run.
B) shut down in the short run.
C) exit the market in the long run.
D) continue to operate in the long run.
E) both a and c