Figure 15-2 Suppose a firm operating in a competitive market has the following cost curves: A graph of Price versus Quantity, shows a straight line, M C, increasing linearly from (1, 2) to (9, 18), and a curved line, A T C, which decreases at a decreasing rate, reaching a minimum where MC = ATC and they intersect, and then increases at an increasing rate., from (1, 10) to (9, 10). There are 3 horizontal lines that extend from the vertical axis at the following points. $6, $7, and $10. The intersection of M C and A T C is at Q = 3 for P = $6, P = $7 hits the A T C at Q = 5, and P = $10 hits the M C at Q = 5. A vertical line extends from (3, 0) to (3, 10), crossing the intersection of M C and A T C at point (3, 6). A vertical line extends from (5, 0) to (5, 10). Refer to Figure 15-2. If the market price is $6, what is the firm's short-run economic profit? a. $0 b. $12 c. $15 d. $18