Nothing in these Rules shall（）any vessel，or the owner，master or crew thereof，from the consequences of any precaution which may be required by the ordinary practice of seaman，or by the special circumstances of the case.

A.from forward to aft
B.from aft to forward
C.at master's option
D.as per owner's instruction

A.returns the vessel to an even keel
B.reduces free surface effect
C.lowers the center of gravity
D.raises the center of buoyancy

A.where
B.that
C.which
D.whether