Determining the day of the week in a future calendar year

Calculate the accumulated odd days from the century baseline (Dec 31, 2000 was a Sunday). Years from 2001 to 2098 = 98 years. Leap years in this span = 98 \div 4 = 24. Ordinary years = 98 - 24 = 74. Odd days from years = (24 × 2) + (74 × 1) = 48 + 74 = 122. 122 ± od 7 = 3 odd days.

Now, count the odd days for the months of the target year 2099 up to May 31: Jan (3) + Feb (0) + Mar (3) + Apr (2) + May (3) = 11 odd days. 11 ± od 7 = 4 odd days.

Total odd days up to June 1st = 3 + 4 = 7 \equiv 0 ± od 7. Since the baseline was Sunday, 0 odd days means June 1, 2099 is a Monday.

If June 1 is Monday, we count forward: June 2 (Tue), June 3 (Wed), June 4 (Thu), June 5 (Fri), June 6 (Sat), June 7 (Sun).

Answer: (d).