A vessel engaged in（）shall not impede the passage of any other vessel navigating within anarrow channel or fairway.

A.vessel towing a submerged object
B.dredge underway and dredging
C.hydrographic survey vessel at anchor and surveying
D.None of the above

A.must be lighted
B.may have a flashing red light
C.may have a fixed white light
D.None of the above

A.CCS marine surveyor
B.certified marine chemist
C.port engineer
D.MSA marine inspector