Final answer:
a) Claudius Ptolemy is responsible for inventing the Epicyclic Theory of the Solar System. This theory was part of the Ptolemaic model, which was later replaced by the heliocentric model introduced by Nicolaus Copernicus.
Step-by-step explanation:
The Epicyclic Theory of the Solar System, which describes the movement of small circles upon larger circles, was invented by Claudius Ptolemy. This theory is part of the Ptolemaic model, a geocentric model that places Earth at the center of the universe. The Ptolemaic model was eventually replaced by the heliocentric model proposed by Nicolaus Copernicus, which correctly positions the Sun at the center of the solar system.
In Ptolemy's Complicated Cosmological System, each planet orbits around a small circle called an epicycle. Each epicycle, in turn, orbits on a larger circle called the deferent. This complex system was designed to account for the planetary motions observed in the sky at the time, under the assumption that the Earth was stationary and that all celestial motions had to be circular.