单项选择题 An icebreaker displaying a flag hoist which consists of the code letters “WO” (Whiskey Oscar) is indicating that（）.

单项选择题 An icebreaker assisting a vessel through an ice field would display a visual signal consisting of the code letter “E” (Echo) to signify that “（）”.

单项选择题 An example of an anchor which has a stock is a（）.