Question

Inertia is responsible for :

Answer 1

B. the reason we must wear seat belts

Answer 2

B) we need seat belts to keep us in the car just in case a car breaks suddenly or hits another.

Remember— an object in motion will remain in motion until acted on be another outside force acts upon it
In this case the seat belt is the outside force.

An object will remain at rest until an outside force acts upon it.

Hope this helps!