Which of the following is a symptom of hypoxia?

Dizziness is a classic symptom of hypoxia, which refers to a deficiency in the amount of oxygen reaching the tissues. When the body experiences low levels of oxygen, as seen in hypoxic conditions, it can lead to various physiological responses. One of the earliest signs of inadequate oxygen supply to the brain is dizziness, as the brain is highly sensitive to changes in oxygen levels. This symptom can manifest as lightheadedness, confusion, or a feeling of unsteadiness.

In contrast, while increased heart rate can occur in response to hypoxia as the body tries to compensate for the oxygen shortfall, it is not as specific and direct a symptom as dizziness. Hiccups and fever are not typically associated with hypoxia, as they pertain to different physiological processes and do not indicate the lack of oxygen directly affecting the body's tissues.