What must a driver always do when making a left turn from a center lane?

When making a left turn from a center lane, a driver must signal their intent to turn. This is crucial for informing other road users of the driver's actions, enhancing safety on the road. Using turn signals provides clear communication to other drivers and pedestrians, allowing them to anticipate the movement and avoid potential collisions. Properly signaling not only adheres to traffic regulations but also contributes to the overall flow of traffic by reducing confusion and uncertainty among drivers.

The other choices involve practices that are not aligned with safe driving protocols. For instance, yielding to cars behind is not standard as left turns generally do not prioritize the vehicles behind the turning driver; instead, the focus is on ensuring the turn can be made safely. Turning off headlights can create hazardous conditions, particularly at night or in low visibility. Lastly, changing lanes without warning can jeopardize road safety, as other drivers may not expect such a maneuver. Therefore, signaling remains the most critical action when preparing to make a left turn from a center lane.