Answer:
c. eccentric epicycles
Step-by-step explanation:
In Ptolemaic model is used to study the apparent motion of planets in direct way , by assuming that each and every planet moves on a small sphere or circle , known as the epicycle . And each planet is moved by a system of two spheres one is epicylce and other is different , the center of different circle is called eccentrics . Nested spheres are also present in the Ptolemy's model.