The law of demand is illustrated by a demand curve that is:

1.The demand curve is a representation of the relationship between quantity of a product demanded and:
a. supply.
b. wealth.
c. price.
d. income.
2. The law of demand is illustrated by a demand curve that is:
a. horizontal.
b. downward sloping.
c. vertical.
d. upward sloping.
3. For most commodities, purchases tend to rise with increases in buyers’ incomes, and to fall with decreases in buyers’ incomes. Such commodities are known as:
a. inferior goods.
b. direct goods.
c. average goods
d. normal goods.