B, is appropriate

Gravitational force is not the centripetal force, since the centripetal force is not a fundamental force, but it is a resultant force acting towards the center in a circular motion. So, in the case of earth and sun the attraction is due to the gravitational force, which is equal to centripetal force, but this won’t be true in every situation since gravitational force might not be equal to centripetal forces such as motion inside a circular shell. Thus, gravitational attraction of the sun on the earth is net force

towards the earth which is centripetal force which is appropriate when considered to the option (a).