A drawbridge may use visual signals to acknowledge a vessel’s request to open the draw. Which signal indicates that the draw will NOT be opened immediately?（）.

A.A rapid ringing of a bell for 5 seconds every two minutes
B.A whistle signal of one short，one prolonged，and one short blast
C.A prolonged blast of the whistle at intervals not to exceed one minute
D.A rapid ringing of a bell for 5 seconds，preceded and followed by three separate and distinct strokes on the bell

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

A.A bell signal
B.A gong signal
C.A whistle signal
D.All of the above