What is the primary reason for using seat belts?

Answer: C — To reduce the risk of injury in a crash

The primary reason for using seat belts is to reduce the risk of injury in a crash. Seat belts are designed to secure occupants in their seats during a collision, preventing them from being thrown forward or ejected from the vehicle. This significant function of seat belts has been proven through numerous studies, which show that wearing a seat belt can dramatically decrease the likelihood of serious injuries or fatalities in a car accident. In the context of the other options, avoiding speeding tickets addresses a legal aspect of driving behavior, while preventing vehicle theft is related to vehicle security rather than safety in a crash. Improving gas mileage pertains to fuel efficiency and has no connection to the safety benefits provided by seat belts. Therefore, the correct answer highlights the crucial role seat belts play in enhancing occupant safety during vehicle operations.