Suppose you observe that the price of movie admissions decline and that the number of people attending movies declines as well. If only the demand curve or the supply curve shifts, this suggests that

A) movies are a normal good and incomes have increased.
B) high salaries for Hollywood actors have increased the cost of movie making.
C) movie theaters have experienced an increase in their operating costs due to increases in the minimum wage.
D) admission prices for other types of entertainment, such as live shows and sporting events, have also declined.