So far,several ships have been reported missing _____ the coast of that island.

问题描述:

So far,several ships have been reported missing _____ the coast of that island.
(A) off (B) on (C) around
并请说明原因,

A.off
off the coast 在海面上(靠近海岸的).
on the coast 在岸上,沿岸.
around the coast -- 英语不通,在海岸的四周?没这种说法.