When giving a hand and arm signal for a left turn, how should the hand and arm be extended?

To signal a left turn using hand and arm signals, the proper method is to extend the hand and arm horizontally out of the driver's side window. This position helps other drivers and pedestrians to clearly see your intention to turn left. By extending the arm straight out to the side, it provides a distinct and easily recognizable signal that indicates a left turn is forthcoming.

The other options do not accurately convey the signal for a left turn. For example, an upward position signals a right turn, while a downward position indicates a stop. An inward position does not correspond to any standard signal for turns and might confuse those observing the signal. Therefore, using a horizontal extension is the universally understood method for indicating a left turn.