Keeping a safe distance from the vehicle in front of us is required:

1. Only when the driver is very tired and his responses are not quick enough.
2. In order to drive in the correct lane and at a proper speed.
3. In high speeds only and during stormy weather conditions.
4. Correct answer: In order to prevent a rear-end collision when the vehicle in front stops or slows down.

WhyDistance is needed so you do not hit the car in front when it brakes or slows down. This always matters, not only in bad weather.