aaba
Archaeologists believe that the Dead Sea Scrolls, discovered in Khirbet Qumran between 1947 and 1967 and estimated at almost 2000 years old, provided rare insight into first century С. E. religious communities.
(A) and estimated at almost 2000 years old, provided rare insight
(B) and estimated at almost 2000 years old, provide rare insight
(C) and estimated to be almost 2000 years old, to provide rare insight
(D) and estimated to be almost 2000 years old, provide rare insight
(E) and they estimate them to be almost 2000 years old, providing rare insight
KAPLAN OFFICIAL EXPLANATION:
The phrase estimated at is unidiomatic, so even if you're not sure how to fix it, you can eliminate (A) and (B). The remaining choices provide only one option, estimated to be, so think no more on the issue and look for another problem. To provide in (C) is wrong; try reading it into the sentence to see that this verb tense does not work in context. (D) and (E) present significantly different options. (E) switches the subordinate and declarative phrases of (D) and the original sentence but it's wrong because the original estimated to be is in a subordinate phrase and is parallel with discovered in. The phrase has to remain subordinate based on its position in the sentence. Also, by making provided into providing, (E) subordinates the final phrase and deeply distorts the meaning of the original sentence. (D) survives.