Question

inertia and gravity from the sun keep all planets in position orbit

Explanation:

In physics (a subfield of Natural Science), planets move in orbits due to inertia (their tendency to keep moving) and the Sun's gravity (which pulls them toward the Sun). The term "orbit" is the correct choice as it refers to the path of a celestial body around another, while "position" is too static and doesn't describe the dynamic motion governed by these forces.

Answer:

orbit