Which statements accurately describe the Doppler effect? Select three options.

a. It is used to learn about the behavior of the universe.
b. It was used by Hubble to measure velocities of galaxies.
c. It indicates galaxy motion through light wavelengths.
d. It indicates a galaxy moving toward Earth through red shift. It indicates a galaxy moving away from Earth through blue shift.

The answer is A,B and C

Explanation: it can be use to learn universe behavior,it is also use for the measurements of velocity of galaxy,and is can also be use to indicate,galaxy motion.

Doppler effect,measures the speed which star and galaxy are moving away from us or towards us. It shows the color of wavelength to be either red shift or blue shift.

when it gains or loses electrons

d is the correct answer