Answer:
C. a distant luminous object travels rapidly away from an observer.
Explanation:
Option C is the correct answer.
Redshift is actually observed when a distant luminous object travels rapidly away from an observer.
In redshift, observers actually see an object that is travelling away from them and it has longer wavelength. The opposite is the blueshift where observers see a light traveling towards them and shifted to shorter wavelength.
In astronomy, redshift takes place when the object's visible light travels towards the red end of the spectrum.
