12. The following Figure 9-4 shows the marginal cost curve, the average cost curve, the average variable cost curve, and the demand curve for a firm over different levels of output. The market price is $P.

Refer to Figure 9-4. The total variable cost for the firm at output level OB is _____.

a. BT

b. BKPO c. BK

d. BTVO

13. Refer to Figure 9-4. The firm should shut down if the price falls to _____.

a. OP b. OR c. OS d. OV

Figure 9-4