A firm has developed a new product for which it has a registered trademark. The firm's market research department has estimated that the demand for this product is Q(P,A)=11,600-1,000P+20A1/2where Q is annual output, P is the price, and A the annual expenditure for advertising. The total cost of producing the new good is C(Q)=.001Q2+4Q. The unit cost of advertising is constant at m=1.

What is the advertising level A* for the firm?

a. 400 b.100 c. 250 d. 800