— do you watch TV?— Every day.A. How oldB. How manyC. How muchD. How often

问题补充：

— do you watch TV?

— Every day.

A. How old

B. How many

C. How much

D. How often

答案：

A. How old

B. How many

C. How much

(答案→)D. How often

解析：句意：---你多久看一次电视？---每天。根据答语，问的应该是看电视的频率。How old是问年龄，how many 和 how much 是问多少，只有how often 是问多久一次。