What is the MOST important factor in the changing of the seasons? A. the earth’s tilt toward the sun
B. the heating and cooling of land
C. the Earth’s distance from the sun
D. the amount of rainfall received

A. the earth’s tilt toward the sun

Explanation:

The most important factor in the changing of the seasons on the earth is the earth's tilt towards the sun.

This causes the differences in the amount of insolation which is incident on the earth surface. Throughout the year, as the earth continues to spin, it receives different amount of solar radiation all year round.

The sun is always overhead around the equator. Such regions of the world receives direct insolation and are mostly constrained to a wet and dry season.

Areas above the equator have the sun at an angle. The diffused sunlight present distinct seasons all year round.