Which of the Following Statements Is Correct

Multiple Choice

Which of the following statements is correct?

A) If the buyer of a good gains, the seller must lose an equal amount.
B) The value of goods is objective; it is equal to the cost of supplying the good.
C) Opportunity costs will always be incurred when scarce resources are used to produce a good.
D) Changes in incentives generally have no effect on human behavior.