单项选择题
The wind is ESE，and a sailing vessel is steering NW. Which fog signal should she sound?（）
A.One blast at one-minute intervals B.One blast at two-minute intervals C.Two blasts at one-minute intervals D.One prolonged and two short blasts at two-minute intervals
单项选择题 The term restricted visibility，when used in the Rules，refers to（）.
单项选择题 The term power-driven vessel means（）in these Rules.
单项选择题 The steering and sailing rules for vessels in restricted visibility apply to vessels（）.
