Suppose that a newspaper report indicates that the price of wheat has fallen. For each of the following events, draw a supply-and-demand graph showing the event's effect on the market for wheat. Then state whether the event could explain the observed fall in the price of wheat.
a. A drought has hit wheat-growing areas.
b. The price of rice has risen, so consumers look for alternatives.
c. As a consequence of increasing health concerns, tobacco farmers have begun to plant other crops.