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) a basic asymmetry in the background radiation, related to its origin.
B) the Doppler shift caused by motion of the Milky Way Galaxy through space toward the constellation Leo.
C) microwave emission from cool, primordial (pregalactic) clouds of gas and dust in that direction.
D) the presence of large clusters of galaxies in only one direction.