just finishing/just going to finish

[joham]

--Are you still busy?
--Yes, I'm _______ the report for the manager and it won't take long.
A. just finishing B. just going to finish

The given answer is A. But does B work as well?

Thank you in advance

[Barb_D]

It sure does.

I was working on another task up until now. And now my plans are to finish up the report I started earlier. I was just going to finish it.