Correct Option (C)

The calendar of a year repeats when the cumulative sum of odd days from the reference year reaches a multiple of 7. A normal year contributes 1 odd day, while a leap year contributes 2 odd days.

Calculating the odd days from the year following 2025:

2026 (Normal year): 1 odd day. Cumulative odd days = 1.
2027 (Normal year): 1 odd day. Cumulative odd days = 1 + 1 = 2.
2028 (Leap year): 2 odd days. Cumulative odd days = 2 + 2 = 4.
2029 (Normal year): 1 odd day. Cumulative odd days = 4 + 1 = 5.
2030 (Normal year): 1 odd day. Cumulative odd days = 5 + 1 = 6.
2031 (Normal year): 1 odd day. Cumulative odd days = 6 + 1 = 7.

Since the cumulative sum of odd days reaches 7 at the end of 2031, the calendar for 2031 will be identical to that of 2025.

Incorrect Options:

The calendars for 2029, 2030, and 2033 do not match that of 2025 because the cumulative sum of odd days from 2026 up to the year preceding each of these options does not amount to a multiple of 7:

For 2029: The cumulative odd days up to the end of 2028 is 4.
For 2030: The cumulative odd days up to the end of 2029 is 5.
For 2033: The cumulative odd days up to the end of 2032 would be 9 (7 from 2026-2031 + 2 for 2032), which is 2 when divided by 7. Therefore, 2033 will not have the same calendar as 2025.