Farmer McDonald sells wheat to a broker in Kansas City, Missouri. Because the market for wheat is generally considered to be competitive, Mr. McDonald maximizes his profit by choosing a. to produce the quantity at which average variable cost is minimized. b. to produce the quantity at which average fixed cost is minimized. c. the quantity at which market price is equal to Mr. McDonald's marginal cost of production. d. the quantity at which market price exceeds Mr. McDonald's marginal cost of production by the greatest amount.