During an engine runup with doors open, which symptoms could indicate carbon monoxide poisoning?

The symptoms of dizziness, fatigue, nausea, and headache are classic indicators of carbon monoxide poisoning. Carbon monoxide (CO) is a colorless, odorless gas that can lead to severe health effects, including hypoxia, due to its ability to bind with hemoglobin in the blood more effectively than oxygen. When individuals are exposed to carbon monoxide, especially in a confined space such as during an engine runup with open doors, these symptoms may manifest as the body struggles to receive adequate oxygen.

In contrast, while shortness of breath and chest pain might suggest respiratory distress or cardiovascular issues, they are not specific to carbon monoxide exposure. Visual disturbances and impaired coordination could be associated with various forms of intoxication or neurological disorders, whereas ringing in the ears and muscle cramps are not typical symptoms of carbon monoxide poisoning. Therefore, the symptoms outlined in the correct choice align closely with the known effects of carbon monoxide on the body, making it the appropriate answer in the context of potential exposure during an engine runup.