The greatest acceleration of the planet is at point C. Option C
Does the gravitational acceleration increase as the distance between the planet and the star increases?
Gravitational acceleration does not increase as the distance between a planet and its star increases. According to Newton's law of universal gravitation, the gravitational force between two objects is inversely proportional to the square of the distance between their centers of mass.
The closer the planet is to the star, the more the gravitational acceleration as we can see when we look at the diagram that we have been shown in the image that we have.