單項選擇題

A 200-meter vessel restricted in her ability to maneuver，at anchor，will sound a fog signal of（）.

A.a 5 second ringing of a bell forward and a 5 second sounding of a gong aft at intervals of 1 minute
B.one prolonged followed by two short blasts every 2 minutes
C.one prolonged followed by three short blasts every minute
D.one prolonged followed by three short blasts every 2 minutes

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