A leaky exhaust system should be repaired because it:

Answer: C — May allow dangerous fumes to enter the car.

A leaky exhaust system should indeed be repaired primarily because it may allow dangerous fumes to enter the car. The exhaust system is designed to channel harmful gases produced during combustion out of the vehicle. A leak in this system can lead to carbon monoxide and other toxic gases leaking into the cabin. This is extremely dangerous as carbon monoxide is odorless and can cause serious health issues, including unconsciousness or even death if inhaled in significant amounts. While the other options point to issues that could arise from a malfunctioning exhaust system—such as engine performance and fuel efficiency—the most pressing and critical concern is the safety of the vehicle's occupants. It’s vital for drivers to be aware of the risks associated with these dangerous fumes entering their vehicle and to ensure that their exhaust systems are in good working order to protect against exposure to these harmful gases.