My answer is the Vacoules, but I might be wrong.
If later is was 100 million years ago, later b would be 200 million years ago (because it is 100millions years prior to a). And therefore layer c must b 300 million years ago.
The answer is A because the males sperm determines the sex of a baby.The determines sperm is carrying an X or Y chromosome.
Answer:
Neanderthals
Explanation:
Homo sapiens encountered neanderthals in europe and had offspring.