An entrepreneur's reward is calculated as:
A. The sum of the sales revenue and the cost of production, which includes the opportunity cost of the entrepreneur's time.
B. The product of the sales revenue and the price of the products.
C. The sum of the sales revenue and the cost of production, which excludes the opportunity cost of the entrepreneur's time.
D. The difference between the sales revenue and the cost of production, which includes the opportunity cost of the entrepreneur's time.