37. The ocean bottom, a region nearly 2. 5 times greater than the total land area of the Earth, is a vast frontier thateven today is largely unexplored and uncharted, until about a century ago, the deep-ocean floor was completelyinaccessible, hidden beneath waters averaging over 3,600 meters deep. The word "inaccessible" is closest in meaningto which of following?
(A) unreachable
(B) unrecognizable
(C) unusable
(D) unsafe