I would say b & d are correct. Where is this question from? I've learned that a lot of these
test questions are just plain wrong.
I suppose a could be correct under certain conditions, but based on the really vauge description of the application, I can't see how extending adapter classes wouldn't be appropriate. If you use an adapter as an annonymous class, that's extending an adapter and this happens all the time.
So I also don't see why a is wrong.