Official Solution:Lack of fresh water is an ongoing problem in the outposts, and it is expected to continue until reinforcements arrive. A. (A) Lack of fresh water is an ongoing problem in the outposts, and it is expected to continue until reinforcements arrive.
B. (B) Lack of fresh water is an ongoing problem in the outposts, which was expected to continue until reinforcements arrive.
C. (C) Lack of fresh water is an ongoing problem in the outposts, and they are expected to continue until reinforcements arrive.
D. (D) The outposts lack fresh water, a problem that is expected to continue until reinforcements arrive.
E. (E) The outposts have a lack of fresh water, a problem expected to continue until reinforcements arrive.
(A) The pronoun it has an unclear antecedent.
(B) The pronoun which has an unclear antecedent.
(C) The plural pronoun they could only refer to outposts, which implies that the outposts are expected to continue rather than the problem.
(D) A problem incorrectly refers to fresh water ; it is the lack of fresh water that is the problem.
(E) Correct. A problem correct refers to a lack of fresh water; the sentence is concise and correct. It is not necessary to use that, as in choice D.
Answer: E