The Effect That Makes the Cosmic Microwave Background Appear Slightly

Multiple Choice

The effect that makes the cosmic microwave background appear slightly warmer in one direction and cooler in the opposite direction is

A) the focusing effect of the gravitational field of the local galaxy on the radiation.
B) the presence of many extra sources of the radiation in one direction.
C) a basic asymmetry in the background radiation,related to its origin.
D) the Doppler shift,caused by motion of our Galaxy through space toward the constellation Leo.