Refer to the figure above. Moving from demand curve D2 to demand curve D1 could be caused by a(n):

Refer to the figure above. Moving from demand curve D2 to demand curve D1 could be caused by a(n):
A.increase in consumers’ incomes.
B.increase in the price of a substitute.
C.increase in the price of a complement.
D.increase in quantity supplied.
正确答案：increase in the price of a complement.