Thank you for your feedback. Again the goal here is to give the writer as much feedback for improvement as possible to write these questions closest to the GMAT.
Here are the OA and Explanation - would be fantastic if you could post your feel for the difficulty of this question - let's just put on a level between 600 and 800 - that will of course vary by each test-taker but still:
Below 600
600-650
650-700
700-750
750+
OA: E:The sentence requires a restrictive clause, which is in E – the best answer.
A and B - are wrong as they both are non-restricted clauses.
C - lacks clarity about who were expelled. It also lacks “the”, the definite article, to make sure the items distributed to the 270m refuges.
D - Past perfect tense in D is not required to express a single event in the past. A simple past tense is sufficient.
E - is in simple past and a restrictive clause clearly express that “Much of the food, water and medicine to the 2.75m refugees who live in temporary camps in Darfur were provided by “The NGOs” that were expelled from Sudan”.