Answer:
Redshift in the wavelength of stars happen due to the increasing distance between the celestial objects in lieu to the expansion of the universe.
Step-by-step explanation:
As per the big bang theory the universe is expanding at a very fast rate continuously. All the celestial objects be it planet or stars are moving away from each other. As the galaxies move away from each other the wavelength of the light emitted by stars/luminous bodies with in it increases thereby making the wavelength to fall towards the red part of the spectrum. This shift in wavelength is increasing as the stars/galaxies are moving away from each other. It has been observed that the fainter the star , the more distant it is and hence more will be the redshift in the light emitted by this star.
In this way redshift of distant galaxies best support the big bang theory