The demand curve is downward sloping due to the income effect and the substitution effect. The income effect says:

A.people buy more normal goods when their income increases.

B.people buy more inferior goods when their income decreases.

C.higher prices result in a decrease in the purchasing ability of income, and so less quantity demanded.

D.lower prices result in an increase in the purchasing ability of income, and so greater demand.

E.None of the above