An “atoll cloud” forming over an island due to heating of the land during the daytime would be which type? （）

A.a mattress
B.spilled liquids such as oil or paint
C.high voltage electrical gear
D.a trash can

A.satellite communications
B.navigational information
C.weather information
D.position reporting service

A.At least two lifeboats
B.A radiotelephone
C.A radio direction finder
D.None of the above