Which of the following is a symptom of acute carbon monoxide poisoning?

Acute carbon monoxide poisoning can lead to various symptoms that are often neurological and affect cognitive functions. Behavioral changes are a key symptom of carbon monoxide exposure due to the gas's effects on the brain and nervous system. When carbon monoxide is inhaled, it binds with hemoglobin in the blood more effectively than oxygen, leading to a decreased oxygen supply to the brain. This can cause confusion, dizziness, headache, and altered behavior, which are all indicative of impaired cognitive function.

The other options do not align with the symptoms of carbon monoxide poisoning. Increased appetite, improved concentration, and enhanced physical endurance would not typically be observed in someone affected by acute poisoning, as the individual is more likely to experience fatigue, weakness, and confusion rather than any enhancement in physical or cognitive abilities.