An icebreaker assisting a vessel through an ice field would display a visual signal consisting of the code letter "M" (Mike) to signify that "__________".

Correct Answer: Option D — my vessel is stopped and making no way through the water

Standard icebreaker maneuvering signals using the International Code of Signals designate the single-letter flag 'M' (Mike) displayed by the icebreaker to signify that its vessel is stopped and making no way through the water.