Areas which cannot be scanned by the radar of the vessel because they are shielded by parts of its superstructure, masts,etc means（）.

A.the method for the proper stowage of a dangerous cargo
B.the necessity of lashing, securing and piling of awkward or lengthy cargo
C.whether different goods can be stowed together in one hold
D.ventilation method for hydrous cargo

A.original course
B.initial course
C.final course
D.designated course

A.on
B.in
C.at
D.out