Which atmospheric zone extends from sea level to approximately 10,000 feet?

The physiological zone is the correct answer, as it encompasses the layer of the atmosphere from sea level up to about 10,000 feet. In this zone, humans can function normally without the need for supplementary oxygen. The atmospheric pressure in this range is sufficient to support regular respiration, and the body can effectively exchange gases at this altitude without significant physiological effects.

As altitude increases, the atmosphere begins to thin, which affects the partial pressure of oxygen. The physiological deficient zone, which lies above the physiological zone, indicates an altitude where oxygen levels are lower, and individuals may start experiencing hypoxia without supplemental oxygen. The space equivalent zone begins at even higher altitudes, where the atmosphere becomes more akin to a vacuum, and the stratospheric zone exists above the troposphere, where airplanes generally do not fly as commercial or general aviation aircraft operate primarily within the physiological zone.

Understanding these various atmospheric layers is critical for aerospace physiology, as it guides the necessary precautions and preparations for personnel flying at higher altitudes.