Which of the following is not correct?

a. The producer who requires a smaller quantity of inputs to produce a good is said to have an absolute advantage in producing that good.

b. The gains from specialization and trade are based not on comparative advantage but on absolute advantage.

c. The producer who gives up less of other goods to produce Good X has the smaller opportunity cost of producing Good X.

d. The producer who has the smaller opportunity cost of producing a good is said to have a comparative advantage in producing that good.