In the context of very distant galaxies, what is the dominant cause of the observed spectral shift?

Answer

Cosmological redshift

While Doppler shifts occur due to relative motion, the dominant cause for the large spectral shift seen in very distant galaxies is cosmological redshift, stemming from the expansion of space.

In the context of very distant galaxies, what is the dominant cause of the observed spectral shift?
galaxiesastronomyDistanceredshift