A whistle signal of one prolonged，one short，one prolonged and one short blast，is sounded by a vessel（）.

A.only anchor in the separation zone
B.avoid crossing traffic lanes，but if obliged to do so，shall cross on a heading at as small an angle as is practical
C.avoid anchoring in areas near the termination of the scheme
D.use the separation zone for navigation through the scheme if she is hindering other traffic due to her slower speed

A.intends to alter course to starboard
B.intends to pass starboard to starboard
C.is altering course to starboard
D.intends to pass port to port

A.towing
B.constrained by her draft
C.under sail
D.All of the above