To determine whether a year is a leap year or not, we need to consider the following rules:

1. Rule 1: Any year that is evenly divisible by 4 is a leap year.
2. Rule 2: However, if the year is evenly divisible by 100, it is not a leap year, unless...
3. Rule 3: ...the year is also evenly divisible by 400. In that case, it is a leap year.

Now let's analyze each option to determine which one is a leap year.

a) 2000:
2000 is evenly divisible by 4, so it satisfies Rule 1. Additionally, it is evenly divisible by 100 and 400. Therefore, it satisfies Rule 3 as well. Hence, 2000 is a leap year.

b) 1700:
1700 is evenly divisible by 4, so it satisfies Rule 1. However, it is also evenly divisible by 100, which means it fails to satisfy Rule 3. Therefore, 1700 is not a leap year.

c) 1800:
1800 is evenly divisible by 4, so it satisfies Rule 1. However, it is also evenly divisible by 100, which means it fails to satisfy Rule 3. Therefore, 1800 is not a leap year.

d) 1900:
1900 is evenly divisible by 4, so it satisfies Rule 1. However, it is also evenly divisible by 100, which means it fails to satisfy Rule 3. Therefore, 1900 is not a leap year.

e) None of these:
Since option A, 2000, is a leap year, the correct answer is not "None of these."

In conclusion, the correct answer is option A, 2000, as it satisfies all the rules for a leap year.

A