单项选择题
There are two classes of vessels which，to the extent necessary to carry out their work，do not have to comply with the rule regarding traffic separation schemes. One of these is a vessel（）.
A.engaged in fishing in a traffic lane B.servicing a submarine cable C.towing another D.engaged on pilotage duty
单项选择题 Traffic separation schemes established by the International Maritime Organization（）.
单项选择题 Is it clear（）traffic lane?
单项选择题 The traffic lane（）suspended.
