No one knows there is a small island inhabited by a vast assemblage of animals and plants in that country.
句意：没有人知道那个国家里有一个栖息着一大群动植物的小岛。inhabit栖息。occupied by被…… 占据。live by以……为生。habituate使习惯于。dwell居住，一般与in或on搭配。因此，本题的正确答案为 A。