Answer: The correct answer is A.
The correct answer is C.
Explanation:
Doppler effect is the phenomenon in which there is an apparent change in the frequency of the wave when there is a relative motion between the observer and the source.
Scientists use the Doppler effect to understand the universe by determining the motion of the object.
Therefore, the correct answer is A.
Light changes as the object in space (such as star) moves away from us then the light is shifted to red end. In this case, the light is shifted to longer wavelength.
Light changes as the object in space (such as star) moves towards us then the light is shifted to blue end. In this case, the light is shifted to shorter wavelength.
In the given problem, the when the stars are moving towards each other then the blue shift in the light will occur.
Therefore, the correct option is C.
