During altitude exposure, which of the following symptoms is a sign of potential altitude sickness?

Headache serves as a key indicator of potential altitude sickness, which can arise when an individual is rapidly exposed to high altitudes. This condition, often referred to as acute mountain sickness (AMS), occurs due to a decrease in oxygen levels at higher elevations. The body responds to this hypoxia, and one of the common physiological reactions is the onset of headaches. These headaches can vary in intensity and often result from increased intracranial pressure or changes in brain blood flow due to the lower oxygen availability.

On the other hand, increased energy, enhanced vision, and rapid weight gain do not typically correlate with altitude sickness. An increase in energy suggests improved physiological adaptation to altitude, while enhanced vision is not commonly associated with altitude changes and could be misleading. Rapid weight gain is unrelated to altitude sickness and may point to other health issues, making headache the primary symptom indicating that altitude sickness may be developing.