Right answer: big bang theory
Georges Lemaître, a Belgian physicist and mathematician priest, was the first scholar known to propose the theory of the expansion of the universe.
This theory was postulated from the calculations of the astronomer Edwin Hubble, which is why it has been widely attributed incorrectly to Hubble.
Lemaître proposed what in the future would be known as the Big Bang theory of the origin of the universe, speaking of an infinite past of the universe.
Therefore, the whole sentence is:
Lemaitre (based on Hubble's observations) was the first to suggest the big bang theory
