What gas does a common amoeba emit when breathing?

The common amoeba, like most living organisms, emits carbon dioxide when breathing. The chemical formula of carbon dioxide is CO2, so there was a mistake in the answer options or the correct answer was not indicated. CO is carbon monoxide, which is released during the active oxidation of certain substances and gases. Oxygen is released during the photosynthesis of plants and some animals that have chloroplasts. Nitrogen does not participate in respiration, although it is needed, since it dilutes oxygen, which is poisonous in high concentrations.
Answer: carbon dioxide.