If vehicle 3 has already entered the intersection, what should vehicle 1 do?

When vehicle 3 has already entered the intersection, vehicle 1 must prioritize safety and the right of way. The correct response is to wait for vehicle 3 to pass. This ensures that vehicle 1 does not impede the movement of vehicle 3, which is already navigating through the intersection. Yielding to vehicles that are already in the intersection is a fundamental rule of right-of-way laws, as it helps prevent accidents and promotes orderly traffic flow.

Turning immediately or proceeding without waiting could lead to a collision, as vehicle 1 would potentially enter the path of vehicle 3. Reversing out of the intersection is also not advisable, as it can create confusion and increase the risk of an accident with vehicles approaching from behind. Thus, waiting for vehicle 3 to clear the intersection is the safest and most responsible action for vehicle 1 in this scenario.