What must vehicles turning left do regarding oncoming traffic?

Vehicles turning left must yield to oncoming traffic to ensure safety and prevent collisions. Yielding means that if there are any vehicles approaching from the opposite direction, the driver should wait until those vehicles pass before completing the turn. This is especially important because left turns often cross lanes of oncoming traffic, posing a significant risk if not performed cautiously.

Considering the other options, proceeding regardless of oncoming traffic would disregard the necessary caution required at intersections, potentially leading to accidents. Only looking for pedestrians before turning does not account for the vehicle traffic that must also be considered. Lastly, while checking for traffic signals is important, it does not replace the fundamental rule that vehicles must yield to oncoming traffic during a left turn. Hence, the key principle here is the responsibility of the left-turning vehicle to ensure it does not interfere with oncoming traffic before making the turn.