At which point does the planet have the least gravitational force acting on it?

Point A

Explanation:

Recall that gravitational force is inversely proportional to the square of the distance between the 2 objects.

This means that the farther away the objects are from each other, the lesser their gravitational interaction will be.

In this case we can see that Point A is furthest away from the star, hence this will be the location with the least gravitational force from the star.

carla slowed down in the beginning of her trip, stopped, and then sped up

your answer is, orbit around the nucleus