Although neptune is the farthest planet from the sun, it travels in a fixed orbit around the sun and never changes its path. what is the reason for this? a) the magnetic pull of the sun holds neptune in its orbit. b) the gravitational pull of the sun holds neptune in its orbit. c) the nuclear force acting between the sun and neptune holds the latter in its orbit. d) the repulsive force of bodies outside the solar system holds neptune in its orbit.