Sentence Correction

Even though the state has spent ten years and seven
million dollars planning a reservoir along the Ubi
River, the project will have to be abandoned as a
result of the river becoming so heavily polluted.
(A) will have to be abandoned as a result of the river
(B) is to be abandoned on account of the heavy
pollution which the river received
(C) had to be abandoned because the river had
received such heavy pollution
(D) has to be abandoned because of the river and its
(E) must be abandoned because the river has become