Final answer:
Hypoxia is described as a decrease in the amount of dissolved oxygen in plasma or air, leading to inadequate oxygen levels for tissue health.
Step-by-step explanation:
The statement that most accurately describes hypoxia is: 'a decrease in the amount of dissolved oxygen in plasma or air'. Hypoxia refers to a condition where there is an inadequate level of oxygen reaching the tissues. This can be caused by a variety of factors, including high altitude, respiratory diseases, or issues with blood circulation. It is important to know that while carbon dioxide levels can affect oxygen delivery by influencing blood pH and thereby hemoglobin's affinity for oxygen, hypoxia specifically refers to the oxygen levels themselves, not carbon dioxide.