Answer:
Step-by-step explanation:
There are different theories and evidence about the big bang, in this case, we're going to see three evidence.
The galaxies are moving from us, this means space is expanded, this in consequence Big Bang's explosion.
The cosmic microwave background radiation is related to the early warmth of the universe.
The observed abundance of hydrogen, helium, deuterium, lithium, these are checked from the spectra of the oldest stars.