What must be confirmed about turn signals, 4-way, and marker lights?

The correct choice emphasizes that turn signals, 4-way flashers, and marker lights must be amber in color, clean, and functioning properly. This is important for safety and compliance with regulations. Amber lights are standardized for these functions to ensure visibility and clarity to other drivers on the road.

Cleanliness is crucial as it allows for better light emission and visibility, reducing the risk of accidents due to unclear signaling. Proper functionality ensures that the driver can communicate intentions to others on the road effectively, which is essential for safe driving practices.

Other options do not meet the necessary safety standards. For instance, yellow and cracked lights do not provide a reliable warning or indication and can lead to traffic violations. Merely being functional does not address the condition or color, both of which are vital. Lastly, while some lights need to be red depending on their specific function, turn signals and marker lights are specifically mandated to be amber, making that alternative inappropriate for this context.