Can I have some rice, please?  [ ]

A. Sure. Here you are.

B. Thank you.

C. Everything' s ready.

In radiotelephone communications，the prefix PAN-PAN indicates that（）.

A.a ship is threatened by grave and imminent danger and requests immediate assistance

B.a calling station has an urgent message about the safety of a person

C.the message following the prefix will be about the safety of navigation

D.the message following is a meteorological warning