The correct option is B Monday
No. of days between March 7, 2004 and March 7, 2005 = 365; (2005 is not a leap year; February of 2004 is irrelevant here.)
Thus, the day on March 6, 2005, will be 1 day beyond the day on March 6, 2004.
But, March 6, 2005, is Monday. Therefore, March 6, 2004, is Sunday.
It means that March 7, 2004, must be Monday.