Question

which galaxy is the farthest away?
c
b
d
a

Explanation:

The farther a galaxy is, the greater its redshift. Redshift is indicated by the shift of spectral lines towards longer wavelengths. In the given spectra, galaxy A has the most - shifted spectral lines towards the red - end (longer wavelengths) compared to the others, indicating the greatest redshift and thus being the farthest away.

Answer:

A. A