What is the purpose of white lines painted on highways?

• To separate lanes of traffic moving in the same direction
• To allow passing or lane changes when broken
• To indicate no crossing when solid
• All of the above
  Explanation:

  "White lines are painted upon the highways to separate traffic moving in the same direction. Solid white lines are usually found to the far right or left (carpool, restricted lane, breakdown, parking) of roadways. Passing another vehicle and changing lanes are restricted. Exceptions exist (carpool lane, slow-moving vehicles, hills, breakdown, parking, etc). Broken white lines allow motorists the opportunity to pass other vehicles and change lanes."