How is deoxygenated blood characterized?

Deoxygenated blood is characterized as blood that is lacking oxygen. In the human circulatory system, blood that returns to the heart from the body tissues has delivered its oxygen to the cells and collected carbon dioxide and other waste products. This blood is low in oxygen saturation and is transported back to the heart to be sent to the lungs for oxygenation.

While it is true that deoxygenated blood is rich in carbon dioxide, this does not capture the primary characteristic as succinctly as the option about lacking oxygen. Blood that is low in nutrients is not a defining feature of deoxygenated blood, as nutrients can still be present. Similarly, being saturated with carbon monoxide is not a typical characteristic of deoxygenated blood under normal physiological conditions; it is a condition that arises only in specific scenarios, such as carbon monoxide poisoning. Thus, the key factor that distinctly describes deoxygenated blood is its lack of oxygen.