Which statement describes seat belts?

• A. They keep you safe and in your seat by counteracting inertia
• B. They are optional safety features that do not affect you during a crash
• C. They slow the car’s momentum by friction with the seat
• D. They deploy only after airbags

Answer: (A)

Seat belts work by counteracting inertia—the tendency of your body to keep moving forward when the car stops suddenly. When a crash happens, the car slows down quickly, but your body would keep moving at first. The seat belt provides a restraining force that holds you in your seat, spreading the stopping force over a longer moment and over a larger area of your body. This keeps you from being thrown forward or ejected, reduces the peak forces on you, and helps position you for effective protection from airbags.

That idea is why the best description is that seat belts keep you safe and in your seat by counteracting inertia. They are not optional, they do affect you during a crash, and their primary function isn’t to slow the car by friction with the seat. They don’t deploy after airbags; belts are already engaged, while airbags deploy based on sensing a crash.