Which of the following is an early sign of hypoxia?

Restlessness is indeed recognized as an early sign of hypoxia. When the body does not receive enough oxygen, it can lead to a state of agitation or anxiety. This reaction occurs because the brain is highly sensitive to oxygen levels; as they drop, mental function may begin to deteriorate, causing a person to feel uneasy or restless. This response serves as a warning system, alerting both the individual and caregivers to the presence of hypoxia, facilitating early intervention.

Cyanosis, while a sign of hypoxia, typically occurs later as the body's oxygen saturation decreases significantly. A weak pulse might be indicative of various cardiovascular issues, not exclusively hypoxia. Mental status changes, typically seen as confusion or altered consciousness, indicate a more significant level of oxygen deprivation. Therefore, restlessness stands out as the most immediate and detectable early response to low oxygen levels.