If a towing vessel and her tow are severely restricted in their ability to change course，they may show lights in addition to their towing identification lights. These additional lights may be shown if the tow is（）.

A.It pulls the bow toward the bank
B.It pushes the entire vessel away from the bank
C.It pulls the stern toward the bank
D.It heels the vessel toward the bank

A.toward the inside of the bend
B.toward the outside of the bend
C.toward the center of the river just before the bend，then change course for the river's center after the bend
D.in the river's center

A.dip of the line
B.stretch of the line
C.strain on the line
D.length of the line