Answer: blood transfusion
Explaination:a routine medical procedure in which donated blood is provided to you through a narrow tube placed within a vein in your arm
<span>The skeletal system also protects
internal organs and produces blood cells. Bones provide calcium that is
essential for the proper functioning of the nervous system. ... Sensory receptors in joints between bones send signals about body position to the brain. The brain regulates the position of bones by controlling muscles.</span>
(3) environmental conditions affect gene
<span>expression</span>
Speed. This is more of a physics question.
