Ganymede is one of the many moons of jupiter. it is nearly spherical in shape. it is larger than the planet mercury and slightly smaller than the planet mars. if it is so large compared with the bodies around it, why is it called a moon and not a planet?

1 it is too far from the sun.
2 it is smaller than jupiter.
3 it moves in an orbit around jupiter.
4 it has no gravitational pull.