An element is a pure substance that cannot be separated or divided into simpler substances by any method (physical or chemical). The four common elements in all the living organisms are carbon, oxygen, hydrogen, nitrogen.
Thus, the four elements that make up about 96 % of body matter are carbon, oxygen, hydrogen, nitrogen (c).
Your answer would be D. As the circulatory system pumps oxygen rich blood through the body, and the respiratory system helps you to breath. Hope this helps!
