As observed from the earth, the sun appears to move an approx. circular orbit. For the motion of another planet like mercury as observed from the earth, this would

Options

A. be similarly true.
B. not be true because the force between earth and mercury is not inverse square law.
C. not be true because the major gravitational force on mercury is due to sun.
D. not be true because mercury is influenced by forces other than gravitational forces.

Answer

C

Explanation

The major gravitational force on mercury and earth both is due to the sun that acts as centripetal force. This is the reason why both the planets revolve around the Sun in nearly circular orbits. As earth revolves about sun, to an observer on the earth the sun will appear to be revolving in a circular orbit. Mercury does not appear to be revolving around the earth. So, its motion as observed from the earth cannot be circular because earth does not revolve around it.