822. The root systems of most flowering perennials either become too crowded, which results in loss in vigor, and spread too far outward, producing a bare center.

(A) which results in loss in vigor, and spread
(B) resulting in loss in vigor, or spreading
(C) with the result of loss of vigor, or spreading
(D) resulting in loss of vigor, or spread
(E) with a resulting loss of vigor, and spread

Solution:

OG Solution:
Choice A misuses which: as a relative pronoun, which should refer to a specific noun rather than to the action of an entire clause. A also produces the unidiomatic and illogical construction either... and. Choice B properly uses a verb phrase (resulting ...) instead of which to modify the action of the first clause and also correctly completes either with or, but the verbs following either and or are not parallel: spreading must be spread to match become. Choice C is flawed by the nonparallel verb spreading and the wordy phrase that begins with the result of. Choice E is similarly wordy and uses and where or is required. Choice D--concise, idiomatic, and parallel--is best.


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