How long will the guard circuit remain Yellow after the call is complete?

• A. 3 seconds
• B. 5 seconds
• C. 7 seconds
• D. 9 seconds

Answer: (B)

The concept tested is the guard timer behavior that keeps a circuit in a guard or hold state after a call ends. When a call finishes, the system doesn’t immediately make the line available again; it enters a Yellow guard period so relays can settle and to prevent rapid re-seizure by another user. In this setup, the standard guard time is five seconds, so the circuit stays Yellow for that interval before returning to the ready state. The other durations are not used here because they would either cut the hold too short for proper settling or unnecessarily delay re-use. Thus, five seconds is the correct duration.