What does this hand signal mean when a driver is indicating left?

Answer: A — Turn left

When a driver extends their left arm straight out of the window, it is an established hand signal that communicates the intention to turn left. This signal is recognized universally and helps to ensure that other road users, including pedestrians and cyclists, are aware of the driver's intended action. Using hand signals, especially in situations where turn signals may not be visible or are malfunctioning, is crucial for road safety and communication between drivers. Understanding these signals is important for both safe driving practices and following the rules of the road.