The two reasons early astronomers developed the geocentric model of the solar system are:
C. The model could explain the apparent motions of the Sun and Moon across the sky.
D. The model could explain the apparent backward motion of some of the planets in the sky.
The geocentric model, also known as the Ptolemaic model, was a model of the solar system in which the Earth was at the center and the Sun, Moon, and planets revolved around it. This model was developed by the ancient Greeks and was widely accepted for many centuries. It was able to explain the apparent daily motion of the stars and the annual motion of the Sun across the sky, as well as the apparent backward motion of some of the planets, known as retrograde motion. However, it was eventually superseded by the heliocentric model, which placed the Sun at the center of the solar system and was able to better explain the observed motions of the planets.