The change in seasons on the earth occurs because

Options

A. the distance between the earth and the sun is not constant
B. the axis of rotation of the earth is parallel to the plane of its orbit.
C. the axis of rotation of the earth is perpendicular to the plane of its orbit
D. the axis of rotation of the earth is tilted with respect to the plane of its orbit.

Explanation

### Step-by-Step Solution:

1. **Understanding the Earth's Axis**: The Earth rotates on its axis, which is an imaginary line that goes through the North and South Poles. This axis is not vertical; instead, it is tilted at an angle of about 23.5 degrees relative to the plane of its orbit around the Sun.

2. **Tilt and Orbit**: The Earth orbits the Sun in an elliptical path. The tilt of the Earth's axis remains constant as it travels around the Sun, which means that different parts of the Earth receive varying amounts of sunlight throughout the year.

3. **Seasons Change**: As the Earth orbits the Sun, the tilt causes different hemispheres to receive more direct sunlight at different times of the year. For example:
- When the Northern Hemisphere is tilted towards the Sun, it experiences summer, while the Southern Hemisphere, tilted away, experiences winter.
- Conversely, when the Southern Hemisphere is tilted towards the Sun, it experiences summer, and the Northern Hemisphere experiences winter.

4. **Conclusion**: The change in seasons is due to the tilt of the Earth's axis in relation to its orbit around the Sun, which affects how much sunlight different areas of the Earth receive throughout the year.

5. **Final Answer**: Therefore, the change in seasons on Earth occurs because the axis of rotation of the Earth is tilted with respect to the plane of its orbit.