Explanation:
from the given choices it can only be
the shape of Earth.
at any moment of time, because of the ball shape, there are areas on Earth in full, direct sunlight, areas with dimmer light due to narrower angles of sight to the sun, and areas without any light ("night").
what I am missing here is the inclination of the Earth's rotational axis towards its orbital plane around the sun. that is what changes the angle is sunlight over the year in general creating the seasons in the 2 hemispheres.
