What creates the phenomenon known as red shift?

a. When light emitting bodies move closer to us

c. When light is refracted by solar particles

b. When light emitting bodies move away from us

d. When the amplitude of a wave of light increases

When light emitting bodies move away from us - this is because the light waves being emitted are effected by the bodies movement and the waves are elongated as the body progresses away from the observer, and a longer wavelength results in a shift towards the red end of the spectrum