Which day shapes does the Navy use to signal that divers are in the water?

The correct choice indicates that the Navy uses the Ball-Diamond-Ball day shape in combination with the Alpha flag to signal that divers are in the water.

The Ball-Diamond-Ball shape is specifically designed to convey a warning to other vessels that divers are present in the water. This visible day marker is critical for ensuring safety during diving operations, as it alerts nearby navigation traffic to potential hazards. The presence of the Alpha flag, which signifies “Diver Down; Keep Clear,” complements the Ball-Diamond-Ball shape, reinforcing the message that divers are actively engaged underwater.

While other flags mentioned in the options serve different purposes in maritime communication, they do not specifically indicate the presence of divers in the water. For example, the Bravo flag is used to signal that a vessel is carrying dangerous cargo and the Golf flag is not associated with underwater diving signals. Therefore, the combination of Ball-Diamond-Ball with the Alpha flag is the precise method used by the Navy for signaling diver operations.