The Wheeler Wheat Farm sells wheat to a grain broker in Seattle, Washington. Since the market for wheat is generally considered to be competitive, the Wheeler Wheat Farm maximizes its profit by choosing
选项：

A:a. to produce the quantity at which average variable cost is minimized.;
B:b. to produce the quantity at which average fixed cost is minimized.;
C:c. to sell its wheat at a price where marginal cost is equal to average total cost.;
D:d. the quantity at which market price is equal to the farm's marginal cost of production.