Carbon dioxide because every other option requires an input.
Answer:
In a chemical reaction, the atoms and molecules that interact with each other are called reactants. In a chemical reaction, the atoms and molecules produced by the reaction are called products.
Answer:Capillaries
Explanation: Capillaries are tiny, thin walled vessels that form a network to take blood through the organs and other body tissues. The dense networks of capillaries present a large surface area, which allows materials to be exchanged between body cells and the blood rapidly.
