What must you do if you encounter a double yellow line on your left?

When you encounter a double yellow line on your left, it indicates a no-passing zone. These lines serve as a clear signal to drivers that passing is not permitted due to potential hazards or visibility issues. The presence of a double yellow line means that it is unsafe to attempt to pass another vehicle in that area, as it could lead to dangerous situations, including head-on collisions.

Driving without concern or making a U-turn in such areas would be inappropriate actions, as they disregard the traffic regulations that are designed to maintain road safety. Therefore, the correct action is to refrain from crossing the double yellow line to pass, ensuring adherence to traffic laws and the safety of all road users.