-Bob's Books Is the Only Bookstore in Town

-Bob's Books is the only bookstore in town. The figure above shows the demand curve for books and Bob's Books' marginal revenue curve and marginal cost curve. Bob's Books maximizes its profit and sets the price of a book equal to ________ and has total annual revenue of ________.

A) $40; $40,000
B) $30; $60,000
C) $20, $60,000
D) $10; $40,000