What is the size of the standard red flag used for flagging?

Answer: C — 24 inches square

The standard red flag used for flagging in temporary traffic control applications is 24 inches square. This size is widely accepted and specified in various traffic control guidelines because it provides optimal visibility and identification from a distance. A flag of this size strikes a balance between being large enough to be seen by drivers from afar while still being manageable for flaggers to hold and maneuver effectively. The use of this standardized size helps ensure consistency and effectiveness in communication with drivers, which is critical for maintaining safety in work zones.