单项选择题
A.any sailing vessel with propelling machinery
B.any vessel propelled by machinery
C.any sailing vessel with or without machinery for propelling
D.any sailing vessel with propelling machinery not in use
单项选择题 The steering and sailing rules for vessels in restricted visibility apply to vessels（）.
单项选择题 The Rules state that certain factors are to be taken into account when determining safe speed. Those factors include（）.
单项选择题 The Rules state that certain factors are to be taken into account when determining safe speed. One of the factors is the（）.