Answer:
B
Step-by-step explanation:
due to the limited speed of light we always see objects the way they were in the past, when the light that reaches our eyes right now, was originally sent or reflected by these objects.
we see during the day the sun as it was about 8.5 minutes ago.
when we look into a mirror, we see ourselves how we were a tiny fraction of a second ago.
and when we see a galaxy 100 million light years away, we see it right now as it was 100 million years ago (because that is the meaning of a light year : the distance light travels in a year).
this is the same principle as with sound. just that the speed of light is much faster than the speed of sound, but it is still very much finite.
and because almost all objects out there move away from everything else, we see them red-shifted (because they move away from us, the frequency of the light hitting our eyes is a little bit stretched, making the color of the light move more towards the red end of the spectrum, than what it originally was).
this is like the Doppler-effect in sound (the effect we all have heard when an emergency vehicle with activated siren comes closer and then moves away. and the pitch of the sound goes first higher and then lower).
but careful not everything is moving away from us. the Andromeda galaxy for example is getting closer. we (our galaxy) are on a collision course with it.
so, when looking at that particular galaxy, it is therefore actually blue-shifted