It is dangerous to leave the car engine running in a closed garage, because it may cause serious pollution due to poisoning by emission of

Solution (By Examveda Team)

The extremely high concentrations of carbon monoxide produced by an engine can raise CO concentrations in a closed building so quickly that a person may collapse before they even realize there is a problem.
Carbon monoxide reduces the amount of oxygen to the brain, causing CO intoxication, and lack of reasoning. Hence option D is correct answer.