How long should you wait at a railway crossing after coming to a complete before proceeding?

• Until all the warning signals stop flashing
• Until all the barriers or crossing gates are raised
• Until all the tracks are clear
• All of the above
  Explanation:

  "When stopped at a railway crossing, you must remain stopped until all tracks are clear, all railroad crossing warning signals stop flashing, the crossing gates are raised, and it is safe to proceed."