Why is it important to maintain a "cushion of safety" while driving?

• To make room for more vehicles on the road
• To maintain a constant speed
• To allow space for emergency vehicles to pass
• To have open space in front, behind, and on the sides for safe driving
  Explanation:

  "You should always give yourself a “cushion of safety,” having open space in front, behind and on the sides. Avoid following too closely. Stay far enough behind the next vehicle that, if it should stop suddenly, you can stop safely. Remember that speed, traffic, road and weather conditions will affect your ability to stop."