Suppose that Dave has $200 to spend per week and he buys only magazines and pizza. The price of a pizza is $10 and the price of a magazine is $5. If Dave buys 20 magazines per week, which of the following amount of pizza is not affordable to him?
选项：

A:10
B:20
C:9
D:All of the above answers are correct because none of the listed amounts of pizza are affordable.