For an experiment to measure the volume of \(CO_2 \) that can be exhaled by individuals of varying ages, which of the following would be the MOST appropriate unit of measurement?

Generally, data that deals with gas is measured in liters. Grams is indicative of measurements for solid compounds as they can be easily weighed. The atomic mass unit (amu) is a unit similar to grams but for small, microscopic substances. The pressure unit, atm, is ideal when measuring air pressure, which in this case would not be entirely applicable as the experiment is examining the volume of air that can be expelled from one's lungs, not the pressure of the gas as it comes out of the lungs.[Scientific Reasoning]