The earliest models of the solar system employed what Aristotle

The earliest models of the solar system employed what Aristotle, and Plato before him, had taught was the perfect form: the circle. The simplest possible arrangement -- uniform motion around a circle having Earth as its center -- provided a fairly good approximation to the orbits of the Sun and the Moon. But it could not account for the observed variations in planetary brightness or their retrograde motion. Thus, a more complex model was needed to describe the motion of the planets. a. Argument; conclusion: But it could not account ... their retrograde motion. b. Argument; conclusion: A more complex model ... motion of the planets. c. Nonargument. d. Argument; conclusion: The simplest possible arrangement ... Sun and Moon. https://www.studyhelpus.com/Questions & Answers/models-of-the-solar-system/