Toefl Question

[mamadam]

Hello

Here is my question:

The first Native Americans to occupy <A> what is <B> now the southwestern United States were <C> the Big-Game Hunters, which <D> appeared about 10,000 B.C.


which one is incorrect ? which one is the answer?

the book says the answer is "D", but I don't know why. Besides, I think "B" is the answer because occupy should followed by a location grammatically, so we should use "where is" instead of "What is".

maybe I don't comprehend this sentence!

plz explain

[2006]

Hello
Welcome!
Here is my question:

The first Native Americans to occupy <A> what is <B> now the southwestern United States were <C> the Big-Game Hunters, which <D> appeared about 10,000 B.C.


which one is incorrect ? which one is the answer?

the book says the answer is "D", but I don't know why. Because it should be 'who', not "which". People are 'who', not "which".
Besides, I think "B" is the answer because occupy should followed by a location "the southwestern United States" is a location.
grammatically, so we should use "where is" instead of "What is". no

2006

[mamadam]

Thanks a lot :)