What shape describes each planet's orbit around the sun?

The correct choice is based on the principles of celestial mechanics, specifically Kepler's First Law of Planetary Motion, which states that planets move in elliptical orbits around the sun. An ellipse is a geometric shape that resembles a stretched circle and has two focal points, one of which is occupied by the sun in this context.

This elliptical pathway is fundamental to how planets travel through space, with varying distances from the sun during their orbits. As a result, each planet experiences changes in its orbital speed; it moves faster when it is closer to the sun and slower when it is farther away, all while maintaining this elliptical shape.

Understanding that orbits are not perfect circles is essential to grasping the nuances of planetary motion. While the other choices represent different shapes, they do not accurately describe the nature of planetary orbits in our solar system. For example, a circle would imply constant distance and speed from the sun, which does not align with observed planetary dynamics.