On small sailing vessels，the PRIMARY reason for using nylon in a combination chain-nylon anchor line is to（）.

A.to sail
B.sails
C.sailing
D.sailed

A.Position all personnel at the stern and rock the vessel upright
B.Position all personnel around the mast and lift the vessel upright
C.Lock the centerboard in the down position，stand on the centerboard，and pull on a shroud or a halyard
D.Put the centerboard in the up position and have all personnel haul in on the line attached to the mast

A.By serving
B.By splicing one end of the line around the apparatus
C.Securely attached around the outside in bights no longer than three feet
D.With an approved safety hook or shackle