Quantity Demanded Is on the Horizontal Axis When You Plot

Quantity demanded is on the horizontal axis when you plot a demand curve and shows the:

A) amount of a good that a person is willing to buy at each price.
B) amount of a good that a person actually buys at the market price.
C) amount of a good that a seller is willing to sell at a particular price.
D) amount where opportunity cost is equal to the marginal benefit.