What does this signal indicate?

• The traffic along with public transit vehicles can proceed with caution.
• Public transit vehicles must come to a complete stop while other traffic can proceed with caution.
• The traffic along with public transit vehicles must come to a complete stop.
• Public transit vehicles can proceed while other traffic must come to a complete stop.
  Explanation:

  "Traffic and pedestrians must yield to public transit vehicles at a transit priority signal. This allows transit vehicles to go through, turn right or left, while all conflicting traffic faces a red light."