The correct option is
D Hubble
Since Georges Lemaitre first noted, in 1927, that an expanding universe might be traced back in time to an originating single point, scientists have built on his idea of cosmic expansion. While the scientific community was once divided between supporters of two different expanding universe theories, the Big Bang and the Steady State theory
, accumulated empirical evidence
provides strong support for the former.In 1929, Edwin Hubble
discovered indications that all galaxies are drifting apart at high speeds. In 1964, the cosmic microwave background radiation was discovered, which was crucial evidence in favor of the Big Bang
model, since that theory predicted the existence of background radiation throughout the Universe before it was discovered.