For each of the following, explain whether quantity demanded changes because of a demand shift or a price change, and draw a diagram to illustrate your answer:
a. As a result of increased military spending, the price of Army boots rises.
b. Fish prices fall after the pope allows Catholics to eat meat on Friday.
c. An increase in gasoline taxes lowers the consumption of gasoline.
d. After the Black Death struck Europe in the fourteenth century, wages rose.