Consider the Following Short- Run Cost Curves for a Profit-

Consider the following short- run cost curves for a profit- maximizing firm in a perfectly competitive industry.
FIGURE 9- 2
-Refer to Figure 9- 2.If the price is $6 and the firm is producing at its profit- maximizing output,then total costs for the firm are

A) $300.
B) $1600.
C) $2400.
D) $3500.
E) $100.