What might happen if a pilot exceeds the maximum cabin pressure altitude without oxygen?

When a pilot exceeds the maximum cabin pressure altitude without using supplemental oxygen, the risk of hypoxia becomes a significant concern. Hypoxia occurs when there is an insufficient amount of oxygen available for the body's needs, which can lead to impaired cognitive and physical function. High altitude environments reduce the partial pressure of oxygen, making it harder for the body to absorb oxygen efficiently. As a result, pilots may experience symptoms such as dizziness, shortness of breath, confusion, and a decrease in overall performance.

Utilizing supplemental oxygen helps mitigate these risks by ensuring an adequate supply of oxygen is available for the pilot and the passengers at higher altitudes. Hence, the correct answer underscores the critical importance of oxygen availability in maintaining safe operations at high altitudes.