D. Asteroids vary greatly in size and are mostly made up stone, iron and nickel
Answer:
T3 (tri-iodothyronine) and T4 (thyroxine).
Explanation:
In natural selection, genotype variations that will increase the chance of survival and reproduction of some organism are preserved and will be inherited. If there is no variation, then all individuals have the same chance to survive and nothing will be particularly selected.
