Hi simplyjat,

Yes, definitely this sentence needs to be parallel. I think you're right that the best way of saying this would be "western states" and "eastern states". However, there are more pressing parallel construction issues that render choice B incorrect.

We are trying to say that 10 western states had granted the right to vote, but only one eastern state (or state in the east) had granted the right to vote. So, we need to repeat the word "had" after "east" to keep the sentence parallel.

Thus, only E can be correct.

Remember: the GMAT writers will try to throw you off with things that "sound bad" or "look bad" - focus instead on the grammatical rules.

Thanks for the explanation Jim.

I have one more question. There is something called ellipse construction. Where you omit some words in the repetition. Can't we omit had here?

I think I know what you're saying simplyjat, but I don't think that pertains to this case.

We are trying to compare what the ten western states had done versus what the one eastern state had done.

The original answer compares what the ten western states had done to the one eastern state itself which doesn't work.