Which gas displaces oxygen from the atmosphere and can cause hypoxia and asphyxiation?

Carbon dioxide is known for its ability to displace oxygen in the atmosphere, which can lead to a reduction in available oxygen for breathing. As the concentration of carbon dioxide increases, the partial pressure of oxygen decreases, potentially resulting in hypoxia, a condition where the body does not receive enough oxygen to function. This is particularly hazardous in enclosed spaces or during incidents like combustion where carbon dioxide might accumulate.

While the other options involve various properties and dangers, they do not primarily function as oxygen displacers in the way carbon dioxide does. For example, hexane is a flammable liquid and poses different risks primarily associated with fire and toxicity, but it does not specifically displace oxygen. Argon is an inert gas that also displaces oxygen but is not as commonly associated with hazardous scenarios as carbon dioxide. Ozone, while a reactive gas, presents risks related to respiratory effects rather than displacement of oxygen leading to asphyxiation. Thus, carbon dioxide is the most relevant answer to the question regarding displacement of oxygen and the associated health risks.