Multi-year ice is the hardest sea ice and should be avoided if possible. It is recognizable because of what tone to its surface color? （）

A.around the rudder and screws
B.completely around the vessel
C.to leeward of the vessel
D.to windward of the vessel

A.11 seconds
B.15 seconds
C.20 seconds
D.22 seconds

A.gear extending from the side or stern
B.gear that restricts maneuverability
C.less than 50 percent trolling lines
D.None of the above