15. Madagascar was one of the last habitable areas of the earth to undergo human settlement, which has made it an ideal site for researching rare flora and fauna.
(A) Madagascar was one of the last habitable areas of the earth to undergo human settlement, which has made it
(B) Madagascar was one of the last habitable areas of the earth to have undergone human settlement, and that has made it
(C) Madagascar underwent human settlement as one of the last habitable areas of the earth, which makes it
(D) Madagascar, one of the last habitable areas of the earth, underwent human settlement, making it
(E) Because Madagascar was one of the last habitable areas of the earth to undergo human settlement, it is
看了贴子还是不清楚为什么D不对,多谢指教! | 
