（）is halfway between the forward and after perpendiculars and is reference point for vessel construction.

A.only one high and one low water occur during a lunar day
B.the high tide is higher and the low tide is lower than usual
C.the high tide and low tide are exactly six hours apart
D.two high tides occur during a lunar day

A.Bow breast line
B.Bow spring line
C.Inshore head line
D.Offshore head line