Answer: The different layers are a result of lighter parts (such as the continental crust) settling at the surface level and heavier parts (such as iron and nickel in the core) settling in the middle. The layers separate by density, otherwise known as compositional layering. The earth did not always have these layers, as it had to undergo cooling to form some of them (like the continental crust).
Answer:
C.Because of hunting, species such as bears and wolves are in danger of extinction.
The answer to your question is Insomnia
A biotic factor is all of the students in the classroom.
Hope this helps!!
The answer to this question might be protein.
