Before leaving port on an ocean tow，a tug captain should assure himself of all the following EXCEPT（）.
A. the towing hawser can be released quickly in an emergency
B. the correct navigation lights are rigged and operable on the tug and tow
C. an insurance underwriter has prepared a pre-sailing survey
D. a pick-up wire has been rigged on the tow in case of a breakaway
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