Which of the following years is a leap year?

Explanation

1. 01

   A century year is a leap year only if it is divisible by 400.

2. 02

   $1900 \div 400$, $2100 \div 400$ and $2200 \div 400$ are not whole numbers; $2400 = 6 \times 400$, so 2400 is a leap year.