Final answer:
The Copernican heliocentric model is represented by a diagram with the Sun at the center and planets in orbits around it, which is option A.
Step-by-step explanation:
The heliocentric model of the solar system proposed by Copernicus is best represented by the diagram described as A) A diagram with the Sun at the center, surrounded by planets in circular or elliptical orbits. This model, which contrasts the earlier geocentric model of a universe centered around Earth, places the Sun at the center with the planets, including Earth, orbiting around it.
The Ptolemaic model, in contrast, had Earth at the center and was characterized by complex superpositions of circular paths without a clear cause-and-effect explanation for the motions of celestial bodies. Copernicus's heliocentric model ushered in a new understanding of celestial mechanics, which was later supported by the laws of physics, including Newton's universal law of gravitation.