In a relay operation, which signal indicates readiness?

• A. A whistle from the pump operator.
• B. A written sign-off by the chief.
• C. A verbal confirmation from the spotter.
• D. Clear radio or hand signal confirming connection and flow through all segments.

Answer: (D)

In relay operations, readiness is shown by a clear, explicit signal that all connections are made and water is flowing through every segment. A radio message or a hand signal that confirms the entire line is connected and delivering water ensures everyone knows the system is ready before advancing. This real-time confirmation helps prevent starting pumps or moving gear when part of the line isn’t yet pressurized or properly connected. The whistle, written sign-off, or a single spotter’s verbal cue don’t provide the reliable, all-segments confirmation needed in this setup, whereas a clear radio or hand signal that confirms both connection and flow through all parts does.