—A ruler is 2 dollars and a pen is 3 dollars. How much are they? —They are . A. $2B. $3C.

问题补充：

—A ruler is 2 dollars and a pen is 3 dollars. How much are they?

—They are .

A. $2

B. $3

C. $4

D. $5

答案：

A. $2

B. $3

C. $4

(答案→)D. $5

解析：一把尺子是2美元，一支钢笔是3美元，它们一共多少钱？它们一共5美元，

此题根据句意应该选D。