题目内容：
The phrase "offering a 'brief window of time' for humans to easily cross the sea"(5th paragraph) is closest in meaning to
A． providing a panoramic view of the sea and an easier way to cross i B． Only a small window zone of the sea as little as 2.5 miles wide could be crosse
C． The descending supplied a temporary opportunity to cross the sea easil
D． The sea was as narrow as a window so that people could cross it without effor
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