Correct Answer: Year 2012

Solution : A year is a leap year if it is divisible by 4. So, the divisibility of the given years by 4 is checked.

Let's check the options —

First option: Year 2012; 2012 ÷ 4 = 503. 2012 is divisible by 4. So, it is a leap year. This option is different from the other options.

Second option: Year 1998; 1998 is not divisible by 4. So, it is not a leap year.

Third option: Year 2005; 2005 is not divisible by 4. So, it is not a leap year.

Fourth option: Year 1997; 1997 is not divisible by 4. So, it is not a leap year.

Hence, first option is correct.