It decreases the cost of cars. It increases the speed at which cars can travel. It decreases injuries to passengers in cars. It increases the comfort of passengers in cars.
I gave my students this multiple choice question: Today, almost all cars have seat belts. How does improving the design of seat belts help people the most?

Only one answer is correct among these 4 choices:
- It decreases the cost of cars.
- It increases the speed at which cars can travel.
- It decreases injuries to passengers in cars.
- It increases the comfort of passengers in cars.

Could you tell me which one is correct?

It decreases injuries to passengers in cars.