What signage indicates speed regulation in construction zones?

The correct answer is the orange rectangular sign, which is specifically designed for construction zones. These signs typically provide important information regarding speed limits and other regulations that drivers must adhere to when navigating through areas where construction or maintenance is occurring.

In construction zones, the use of orange is standardized to alert drivers to the increased hazards and potential changes in roadway conditions. This color is visible and signifies caution, indicating that drivers should reduce speed and remain vigilant for workers and construction equipment.

The other options pertain to different traffic control purposes: the red octagon is universally recognized for 'STOP' signs, signaling drivers to come to a complete halt; the yellow diamond with a black arrow typically indicates a general warning about changing road conditions or potential hazards. The green circular sign is generally used for traffic regulations and directions, such as 'go' or 'proceed' at intersections, and does not convey the specific warnings associated with construction zones. Understanding these distinctions helps in recognizing and responding appropriately to various traffic signs during driving.