i think it is rainfall but am not sure...
Explanation:
In all living system we can always find basic elements carbon, oxygen, nitrogen and hydrogen, carbon is the basic building unit contained in living matter. The percentage of carbon in the mass of living matter is 19.0% oxygen and hydrogen are present in almost all organic compound which creates living organisms.
Lack of light in the depths of the ocean does not mean life does not exist at such depths. Marine biologist have found numerous interesting (and slightly nightmareish) life forms at various depths.
The skeletal system works as a support structure for your body. It gives the body its shape, allows movement, makes blood cells, provides protection for organs so I would say the first choice, hopefully I helped out !:)
Protin is made from amino acids.
