Why are thresholds of increasing complexity important in Big History?

Choose 1 answer:

(Choice A)
A
They explain how the Universe and stars formed after the Big Bang.

(Choice B)
B
They show how humans evolved from a primate ancestor to increasingly complex humans.

(Choice C)
C
They explain times when something entirely new appeared in the Universe that greatly impacted events that followed.

(Choice D)
D
They show us what happened every billion years since the Big Bang.