By which of the following a leap year must be divisible

Options

A. 9
B. 6
C. 5
D. 4

Answer

To determine by which number a leap year must be divisible, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Leap Year**: A leap year is a year that has 366 days instead of the usual 365 days. This extra day is added to the month of February, making it 29 days long.

**Hint**: Remember that leap years occur every 4 years, with some exceptions.

2. **Divisibility Rule**: For a year to be classified as a leap year, it must be divisible by 4. This means that when you divide the year by 4, there should be no remainder.

**Hint**: Think about how you can check if a number is divisible by another number.

3. **Complete Weeks and Extra Days**: In a leap year, there are 52 complete weeks (which is 52 x 7 = 364 days) and 2 extra days. This reinforces the idea that a leap year has an additional day beyond the standard weeks.

**Hint**: Consider how many days are in a week and how that relates to the total number of days in a leap year.

4. **Conclusion**: Since a leap year must be divisible by 4, we can conclude that the correct answer to the question is option D, which is 4.

**Hint**: Always check the options provided to ensure that your conclusion matches one of them.

### Final Answer:
A leap year must be divisible by **4**.