845. The utility company has announced that it will permanently close its Unit I nuclear power plant, the first plant that had been built by private industry and the model for a generation of modern nuclear reactors.
(A) that had been built by private industry and
(B) built by private industry and which was
(C) to be built by private industry and which was
(D) built by private industry and
(E) to have been built by private industry and was
Can you please explain why the answer is d and not e? (I don't like e but d also sucks because 'built by private industry' is a participial phrase and 'the model for a generation of modern nuclear reactors' is an appositive. Where's the parallelism?)