How did Claudius Ptolemy improve Aristotle's model of the universe, and what was still incorrect about his model?

Question

Ptolemy suggested that planets orbited the sun, which explained retrograde motion, but he incorrectly thought that stars moved in small circles called epicycles.
Ptolemy suggested that planets moved in small circles called epicycles, which explained retrograde motion, but he incorrectly placed Earth at the center of the universe.
Ptolemy proposed that planets moved in straight lines before reversing direction, which explained retrograde motion, but he did not include the sun in his model.
Ptolemy introduced the concept of elliptical orbits for planets, which explained retrograde motion, but he failed to account for the constant brightness of stars.

Answer 1

Claudius Ptolemy improved upon Aristotle's geocentric model of the universe by introducing the concept of epicycles. He suggested that planets moved in small circles (epicycles) as they revolved around the Earth in larger circles (deferents), which helped explain the observed retrograde motion of planets—where planets appear to move backward in their orbits temporarily. However, Ptolemy still incorrectly placed the Earth at the center of the universe, a fundamental aspect of his model that was later corrected by the heliocentric model proposed by Copernicus.

Therefore, the correct choice regarding Ptolemy's contributions and errors is:

Ptolemy suggested that planets moved in small circles called epicycles, which explained retrograde motion, but he incorrectly placed Earth at the center of the universe.