We need to find the 5th day from the 21st of the month: $21 + 5 = 26$, so we need to find the 26th day of the month. $26 - 3 = 23$, meaning there are 23 days between the 3rd (Monday) and the 26th (required day). 23 days = 3 weeks and 2 extra (odd) days (since 3 weeks contribute 21 days, leaving 2 extra days). Starting from Monday, adding 2 days gives: Monday + 1 day = Tuesday Tuesday + 1 day = Wednesday Thus, the 26th day is Wednesday, so the correct answer is C. Wednesday.