John Maynard Keynes was the author of the book, The Economics of Welfare, which first addressed environmental problems in terms of externalities

A firm's total revenue

a. is the profit it earns by producing and selling a particular quantity of output b. varies as output varies along the demand curve the firm faces c. is constant at all points along a fixed demand curve d. is determined by subtracting total profit from total cost e. always decreases as its output increases, because costs rise

You are the manager of a firm that produces output in two plants. The demand for your firm's product is P = 20 ? Q, where Q = Q1 + Q2. The marginal costs associated with producing in the two plants are MC1 = 2 and MC2 = 2Q2. What is the profit-maximizing price that the firm should charge?

A. $11 B. $12 C. $9 D. $8