Assume That Marginal Revenue Equals Rising Marginal Cost at 100

Assume that marginal revenue equals rising marginal cost at 100 units of output. At this output level, a profit-maximizing firm's total fixed cost is $600 and its total variable cost is $400. If the price of the product is $10 per unit and the firm produces 100 units, the firm will earn an economic profit of

A) zero.
B) $400.
C) more than zero but less than $100.
D) $100.
E) more than $100.