【单选题】
Vessels shall be deemed to be in sight of one another only when one（）from the other.
A、can be observed visually
B、can be observed by radar
C、can be located on the radar
D、can be heard
查看正确答案
A、is ready to use but vessels must stand clear B、is ready to use and vessels may approach C、cannot be made ready immediately and vessels shall stand clear D、cannot be made ready immediately but vessels may approach
