Well, my experience of PL explain was in fx options, but I imagine you would do a similar exercise in equity options. I never encountered the issue, but I don't think that exchange/OTC option type really affects the idea described above, which is basically just an explanation of change in option value as a function of its underlyings.
Finally, I didn't work in MO and I am reluctant to speculate on MO responsibilities - I think there are other contributors with that experience. The whole MO exercise is, I am sure, bigger than the question I answered (ie "what is PL attribution?"), but I would also be thinking about things like portfolio changes, funding, dividends, cash positions, etc.
Good luck with the interview