What does hypoxia refer to?

Hypoxia specifically refers to a deficiency in the amount of oxygen reaching the tissues. This can occur due to various reasons, such as inadequate oxygen supply from the lungs or issues with blood circulation. When tissues do not receive enough oxygen, it can lead to cellular dysfunction and, ultimately, if severe or prolonged, tissue damage or death. Understanding hypoxia is crucial in fields related to health care and nutrition, as it can impact the body's overall metabolism and ability to utilize nutrients effectively.

The other choices do not accurately define hypoxia. For instance, low CO2 levels pertain to a different physiological state and do not directly indicate oxygen deficiency. High oxygen saturation suggests an abundance of oxygen in the blood, which contrasts with hypoxia. The inability to breathe deeply might indicate respiratory issues but does not inherently denote low tissue oxygen levels. Therefore, option C effectively defines the condition of hypoxia.