present perfect continuous v.s. present perfect simple

Hi, everyone!
Here the task for exercise I’ve been doing: Are the underlined verbs right or wrong? Correct them where necessary.

  • I gave up drinking coffee. I don’t drink it for a year.

I answered “I haven’t been drinking it for a year”, but keys give “I haven’t drunk it for a year.”
I wonder why present perfect simple?
As I know, we use present perfect simple when we interested in the result,
and present perfect continuous when we interested in the activity and how much time someone has been doing something.

Thanks in advance.

“I don’t drink it for a year” is normally incorrect.

“I haven’t been drinking it for a year” is not impossible, but “I haven’t drunk it for a year” is probably more usual. I guess you can argue that the failure to do something is not a continuous activity, so does not need a continuous tense.