Which mark indicates a red rag?

The correct mark indicating a red rag is the 17 mark. In naval terminology, specific marks are designated for different purposes, and among these, the 17 mark is associated with signaling the presence of a red rag. This is crucial for communication during operations, as the red rag serves as a warning or caution signal, especially in various maritime situations. Understanding these signals is critical for maintaining safety and operational awareness on the water.

The other marks do not specifically denote a red rag; they are associated with different colors or signals that serve alternate purposes in naval operations. Recognizing and understanding the significance of these marks is essential knowledge for a Boatswain's Mate First Class, as effective communication and safety practices are fundamental to successful maritime operations.