Which statement concerning the navigation of a vessel in ice is FALSE?（）
A.Anchoring in the presence of ice is not recommended except in an emergency
B.Towing a vessel through an ice field is not recommended except in an emergency
C.The "Free and Proceed" system of escorting a beset vessel cuts down on the number of freeing operations
D.When anchoring in ice，it is advisable to increase the scope of the chain over what is normally used for non-icing conditions
