Though it is now universally accepted that William Shakespeare was a

HERE IS OE

In the original sentence, the relative pronoun "which" must stand for the nearest noun or noun phrase preceding the comma or dash, but we cannot refer to a “person” with the pronoun “which.” Rather, the pronoun “who” would have to be used, if that were the intended meaning (though that meaning itself would be illogical). Logically, the fact that “Shakespeare was a real person” (a clause) was in question. Additionally, the original sentence contains two incorrect idioms: "attributed as his own" (the correct idiom is "X is attributed to Y"), and "suspect … not to have written" (the correct idioms are "suspect that…" and "suspect X of VERBing").

(A) This choice is incorrect for the reasons described in the paragraph above.

(B) This choice contains four idiom errors: "accepted to be…", "attributed to be…", "considered as…", and, finally, "suspected not to have…" (the last of which is also present in the original). In addition, it is unclear what is being modified by the modifier “once considered as questionable”, which appears to indicate that the “real, historical person” himself was once considered questionable.

(C) The main part of the sentence – not the part between the dashes – is not a complete sentence. There is no verb to match the subject William Shakespeare. Additionally, there is no change of tense in the first clause (i.e., Shakespeare's existence is not indicated by any past-tense verb); since the timeframe of the rest of that clause is “now”, this construction illogically suggests that Shakespeare is now a real, historical person (i.e., that he is still alive). Finally, the original idiom error "suspected not to have…" has not been corrected.

(D) CORRECT. All of the idiom errors in the original sentence have been corrected: "accepted", "considered", "suspected", and "attributed" are all used in properly idiomatic forms. Additionally, the modifier set off by dashes very clearly indicates which fact is being described, and the use of an appositive ("a fact that…") allows the modifier to refer to the entire idea of the previous clause, as required by context.

(E) This choice preserves the incorrect idiomatic usage of "attributed as…" from the original. In addition, the placement of the modifier at the end of this sentence makes it unclear exactly which fact was once considered questionable; this appositive could conceivably refer either to "it is now universally accepted that he was a real, historical person" (the intended referent) or to "some still suspect that William Shakespeare did not write all of the works attributed as his own".