-- is your cousin?--She’s fifteen years old.A. HowB. How oldC. How manyD. How much

问题补充：

-- is your cousin?

--She’s fifteen years old.

A. How

B. How old

C. How many

D. How much

答案：

A. How

B. How old

(答案→)C. How many

D. How much

解析：本题回答语的含义为我的表妹15岁，表示的是年龄，对此提问的用how old，意思为你的表妹多大了，故本题选B。