The answer choice is E.
However, in the chapter it was discussed that the uncertainty should not be changed. The original question does contain should so the answer have to have it.

Please explain why D is not a correct answer by the above logic.

Thanks a ton.[/u]

Unfortunately, for legal reasons, we can't post and explain OG questions on the web site. If you are one of our students, please ask during office hours or before or after class.

And just to make sure - you posted this in the "ManhattanGMAT Verbal Guides" folder but you labeled the question OG Verbal. If this is from our red strategy guide, please post the question in full, labeled properly, and we'll answer. If it is, in fact, an OG question - see above.