微观经济学的需求问题

有这样一个题~我不太懂：

1. Which of the following will not change the demand for movie tickets?

A. A change in the cost of babysitting services.

B. A change in the incomes of moviegoers.

C. A change in the price of movie tickets.

D. A change in the quality of television programs.

E. A change in the quality of movies.

为什么答案是C，请哪位高手给我详细解释一下~~谢谢

c的话是引起需求量的变动。其他的都是引起需求的变动。