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.

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

答案是E没问题，但想问为什么用to undergo human settlement修饰habitable areas，若改成that underwent human settlement可以么？请NN们指教。

改后的that是修饰earth还是areas啊?

歧义