Earth's core is mainly composed of A:iron and aluminum.
B:silicon and hydrogen.
C:iron and nickel.
D:silicon and oxygen.

C

Explanation:

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: