We are asked which of the given options is most responsible for the changes in seasons.
The reason behind having different seasons is the fact that the Earth's axis is tilted at an angle of about 23.4 degrees. Due to this tilt, different parts of the world receive different amounts of solar radiation.
Those who live closer to the poles experience extreme winters whereas those who live closer to the equator experience hotter summers.
Therefore, the correct answer is option D.
The tilt of Earth on its axis is most responsible for the changes in seasons.