Perhaps or Maybe or I Guess/Think - which one is correct in formal (office) email writing

Question

Background:

Boss: Did you get that X thing done?

Me: Yes, thats done.

Boss: No thats not done, I am still getting calls from people for X?

Me: Oh, Perhaps/Maybe/I guess/I think you are asking about Y thing.

Here I was chatting with my boss, I doubt what should I use out of these, if I want to make it more formal chat/email?

If none are correct, please suggest.

Answer 1

To be as polite as possible you want to keep the option that it was your fault, not his. I would use Perhaps. "Perhaps you are talking about 'Y'" Or else "I think you may be talking about 'Y'"

With these you could add "I'm sure I took care of 'X' for this reason." But be sure X is not still out there.