What is the distance we are required to keep from the vehicle in front of us while driving?

1. A Any distance that allows us to see the back wheels of the vehicle in front of us while driving.
2. B Any distance that always allows us to see well what’s happening ahead of the vehicle that is driving in front of us.
3. C The required statutory distance in which accident may always be prevented, while taking all the relevant elements into consideration.
4. D A distance which prevents entry of other vehicles in it.