Correct option is A
Given:
The date was Sunday on 01-01-2012.
Logic:
2012 is a leap year because it is divisible by 4.
A leap year has 366 days, while a normal year has 365 days
A normal year gives 1 odd day.
A leap year gives 2 odd days (since 366 ÷ 7 = 52 weeks and 2 days).
Starting from 01-01-2012 (which was a Sunday), adding 2 odd days,
Sunday + 2 = Tuesday.
So, 01-01-2013 was a Tuesday.
Thus, the correct answer is (a).