Question

Which evidence supports the big bang theory? the existence of cosmic microwave background radiation light coming from galaxies shifting toward blue atomic spectra analysis showing the universe to be 50% hydrogen, 50% helium

Answer 1

I would say Cosmic microwave background radiation because there are three main theory's and this is the only one I see, there are a thousand theories but this is one of the main theory's. 

Answer 2

A. the existence of cosmic microwave background radiation