Which of the following is a leap year under the Gregorian rule (divisible by 4 except century years must be divisible by 400)?

Introduction / Context:
Century years (ending in 00) are leap years only if divisible by 400. This corrects the over-count that would arise from applying a pure “divisible by 4” rule.

Given Data / Assumptions:

• Test years: 1800, 2600, 2800, 3000 (all centuries).
• Leap if and only if divisible by 400.

Concept / Approach:
Compute each ÷ 400. Only those with zero remainder are leap years; the rest are common years.

Step-by-Step Solution:

Verification / Alternative check:
Known examples: 2000 (divisible by 400) was leap; 1900 (not divisible by 400) was not leap.

Why Other Options Are Wrong:
1800, 2600, 3000 fail the divisible-by-400 condition, hence are common years.

Common Pitfalls:
Applying the “÷4” rule to centuries without the necessary 400 check.

Final Answer:
2800.