Why Are We So Sure the Early Universe MUST Have

Multiple Choice

Why are we so sure the early universe MUST have had some fluctuations in density?

A) The existence of galaxies shows empirically that these density fluctuations must have been present. Theoretically the early universe was expected to be perfectly smooth.
B) These fluctuations are required by the Heisenberg uncertainty principle.
C) Mutual gravitational attraction will always lead to lumpiness, even in a distribution that is perfectly uniform.
D) This is related to the imbalance of matter and antimatter. This led to nonuniform annihilation reactions, and gravitational attraction led to collapse and lumpiness.