If the Price of Output for a Price Taker Is

If the price of output for a price taker is $9 and the marginal cost of the last unit produced is $8.50,then the

A) extra benefit of the last unit produced is less than the extra cost.
B) firm should lower its output to increase its profit.
C) firm is earning an average profit of $0.50.
D) extra benefit of the last unit produced is greater than the extra cost.
E) firm is earning a positive profit.