Answer:
Water.
Step-by-step explanation:
The body of the living organism constitutes the element like hydrogen, oxygen, Nitrogen and Carbon. These elements are important for the proper functioning of the body.
The substance that makes the 75 to 90% of every cell is water. Water is made of hydrogen and oxygen element. The water dissolves most of the solutes of the body and maintains the cell permeability. The water maintains the integrity and structure of the cell as well.
Thus, the answer is water.