What factor causes the seasons? A: Rotation of earth's axis B: The tilt of earth's axis with respect to the sun C: The appearance of the moon D: An eclipse

The correct answer is "B: The tilt of earth's axis with respect to the sun".

In fact, the Earth's axis is tilted by approximately 23 degrees. As a consequence, the rays of light from the Sun hit the Earth's surface with a different angle in different season. In summer season, they arrive more perpendicular to the surface releasing more heat, while in the winter season they arrive more inclined so they release less heat to the Earth's surface.