To avoid carbon monoxide poisoning, drivers should:
- Have their exhaust system checked regularly to be sure it does not leak.
- Keep their car turned off when it is enclosed in a garage.
- Close vents when following closely behind another car.
- All of the above. ✓
Answer: D. All of the above.
All of the above — every one of these habits helps prevent carbon monoxide poisoning, so do all of them.
Why this is the answer
The handbook warns that cars make carbon monoxide, a deadly gas, and lists what not to do: leave the motor running in a garage, leave vents open when you are following another car closely, run the motor with the windows shut while parked, drive with a bad muffler or exhaust system, or run the heater or air conditioner in a parked car with closed windows in an enclosed space. Checking the exhaust for leaks, shutting the car off in a garage, and closing the vents behind another car all match that list.
Why the other answers are wrong
- A. Have their exhaust system checked regularly to be sure it does not leak. — This one is good advice and is part of the answer, since the handbook says not to drive with a defective muffler or exhaust system, so it cannot be the single best choice.
- B. Keep their car turned off when it is enclosed in a garage. — This one is also correct and included in the answer, because the handbook says not to leave the motor running in a garage, so picking only this leaves out the other safe habits.
- C. Close vents when following closely behind another car. — This one is correct too, since the handbook warns against leaving vents open while following closely behind another car, so it is only one part of the full answer.
Remember it
Think of carbon monoxide as a gas you keep out and air out: no idling in a closed garage, no leaky exhaust, and shut the vents when you tail another car.