Even Though the Hubble Law for Galactic Motions Indicates That

Even though the Hubble law for galactic motions indicates that the spectra of all galaxies should show redshift as a consequence of the general expansion of the universe, the Andromeda Galaxy M31 appears to show a blueshift in its spectrum. Why is this?

A) M31 has an abnormally powerful black hole at its center that gravitationally blueshifts its entire spectrum.
B) The mutual attraction between M31 and the Milky Way Galaxy has overcome the general Hubble flow.
C) Young giant spiral galaxies such as M31 do not follow the normal Hubble flow because they have formed relatively recently.
D) One side of M31 is heavily obscured by dust and gas and the blueshift simply shows the Doppler shift of the other side of the galaxy, produced by galactic rotation.