Answer:
C.) Selective pressure
Explanation:
Selective pressure is a natural process that occurs in nature in which certain phenotypes are favored in certain environments. When we say these phenotypes are favored, this means individuals with these phenotypes have a better chance at survival and reproduction in particular environments. Certain phenotypes may be beneficial in some environments but harmful in others.
The notable
hardness of bone is attributed to the presence of inorganic hydroxyapatites.
Due to the calcium salts deposited in it, resulting to the hardness. The
abnormal hardness of bone, which allows it
to resist the compression.
I believe the answer is Integumentary, Hope this helps ")