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 am hesitating between 4 options to answer the following question, which option should I choose?
Question: Today, almost all cars have seat belts. How does improving the design of seat belts help people the most?
Possibilities:
- 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.

It decreases injuries to passengers in cars.