Question

which product of respiration is considered waste material and leaves the alveoli?
oxygen
water
carbon dioxide
carbon monoxide

Explanation:

During respiration, cells produce energy by breaking down glucose. The process of cellular respiration produces carbon dioxide ($\ce{CO_2}$) as a waste product. In the alveoli of the lungs, gas exchange occurs: oxygen enters the blood, and carbon dioxide (the waste from respiration) moves from the blood into the alveoli to be exhaled. Oxygen is taken in, not a waste. Water is a by - product but not the main waste leaving alveoli as gas. Carbon monoxide is not a normal respiration product.

Answer:

carbon dioxide (the option with "carbon dioxide" text)