Answer:
The presence cosmic microwave background (CMB) proved the predictability of the big bang theory.
Step-by-step explanation:
Cosmic microwave background is that heat that is left after a cooling process. The Big Bang theory that was formulated stated that as this whole universe expands, the gases within it cool down.
Accordingly, the whole universe should be filled with radiations that is equal in amount to the heat that is let out. The CMB radiations are literally found everywhere and have a very low temperature which is always constant. This never changing constancy in temperature cannot be found anywhere else which proves the theory of Big Bang.