What action is prohibited by the 'No left turn' sign?

The 'No left turn' sign specifically indicates that drivers are not permitted to make a left turn at the intersection where the sign is posted. This sign is designed to enhance traffic flow and safety by preventing drivers from executing turns that may conflict with oncoming traffic or create hazardous situations. Recognizing and adhering to these signs is crucial for maintaining orderly movement on the roads and minimizing the risk of accidents.

The other actions listed do not directly relate to the specific restriction imposed by the sign. While turning right at the intersection or proceeding straight would typically be permissible unless otherwise stated, the focus of the 'No left turn' sign is solely on the prohibition of left turns. Understanding the implications of road signs like this helps ensure compliance with traffic regulations and safe driving practices.