GMAT Sentence Correction (SC) | Re: Under the Safe Drinking Water Act, the Environmental

886.Under the Safe Drinking Water Act, the Environmental Protection Agency is required either to approve individual state plans for controlling the discharge of wastes into underground water or that they enforce their own plan for states without adequate regulations.

(A) that they enforce their
(B) for enforcing their
(C) they should enforce their
(D) it should enforce its
(E) to enforce its