A demand curve slopes downward to the right because

Select one:

a. n increase in the price of complementary goods causes a decrease in the quantity of this good purchased.

b. an increase in the price of complementary goods causes an increase in the quantity of the good under consideration purchased.

c. monopolists like to charge a high price.

d. as the price of the good under consideration decreases, consumers tend to switch their consumption away from substitutes and toward this good.

e. changes in the price of the good under consideration can encourage producers to produce more.