I would use option B. I count "one year" as 365 days. If you add 365 calendar days to February 29 2004 you end up with March the first, 2005.
Contradictory to this however, if it were 29-2-04 and somebody was to ask me "What are you doing in one year and one day from now?" I would probably assume they were talking about March 1st, 2005.
Similar to how ValSpy pointed out, if it was 29-2-04 and you added
4 years and 0 days, you would still end up with February 29 (2008), whereas adding four years and one day would conclude with the date being March the first, also in 2008.
Sorry to argue both sides here, it really is a good dilemma
My final 'gut' answer is option B, but only in the case where it is going from one leap year to the next 'non-leap' year.
Note: Does the title suggest there are going to be other dilemmas?