Inuits of the Bering Sea were
in isolation from contact with Europeans longer than Aleuts or Inuits of the North Pacific and Northern Alaska.
A) in isolation from contact with Europeans longer than
B) isolated from contact with Europeans longer than
C) in isolation from contact with Europeans longer than were
D) isolated from contact with Europeans longer than were
E) in isolation and without contacts with Europeans longer than
The first split you're likely to notice is that between
in isolation from and
isolated from.
Isolation is a noun, and in this sentence
isolated is a modifier. The modifier is usually better than the noun in such circumstances, especially when the noun is an action noun such as
isolation. Exceptions are common enough that I generally set that issue aside to look for another split. In fact, I generally consider all issues of concision last. But I have a fair degree of confience in this split, and so will eliminate A, C, and E.
The only difference between B and C is the word
were in D. Grammatically, B is ambigious between
Inuits were isolated from contact with Europeans longer than from contact with Aluets and
Inuits were isolated from contact with Europeans longer than Aluets were isolated from contact from Europeans. D is unambiguous. Choose D.
A couple of additional points: First, for more info on choices among action nouns, modifiers, and verbs, see pages 207-211 of our Sentence Correction Strategy Guide. Second, B above may be no more ambiguous than are some right answers. It's only bevause of the split between B and D that we considered ambiguity here. You shouldn't go out hunting for it.