Ali: I watched a documentary last night. It was about the Big Bang.
Zeynep: What is that?
Ali: It is the theory that the universe began from a very hot and dense point about 13.8 billion years ago and has been expanding ever since.
Zeynep: So, the universe is getting bigger?
Ali: Yes! And galaxies are moving away from each other.
Zeynep: That means one day the universe might stop expanding?
Ali: Some scientists think it might keep expanding forever, others think it might start shrinking.
According to the dialogue, which statement is a direct observation mentioned by Ali, rather than a part of the Big Bang theory or a speculation?
A)The universe began from a hot dense point.
B)The universe is 13.8 billion years old.
C)Galaxies are moving away from each other.
D)The universe might keep expanding forever.