The correct answer among the choices given is the last option. Galaxies are classified according to their shapes or visual morphology. There three main types of galaxies currently. They are the elliptical, spiral and irregular. Elliptical galaxies are like a spheroid or an elongated sphere. Spiral galaxies are characterized and distinguished by having a bulge, a disk and a halo. Lastly, irregular galaxies do not have regular or symmetrical shape.