All agreed Richard, whose real name was Richard Penniman, was a pioneer of rock’n’roll, classed with the true greats of the genre.A) All agreed Richard, whose real name was Richard Penniman, was a pioneer of rock’n’roll, classed with the true greats of the genre. ---
There is a difference between “classed with” and ‘and classed with”. In the given context ‘classed with” is a past participle while ‘and classed with’ is a V2 past tense verb whose doer is Richard. Since it would not have been so that Richard might have classed himself reflexively, the V2 past tense doesn’t sync with the meaning of the sentence. We do require a simple modifier at the end.
That is why A is good. B) All agreed Richard, whose real name was Richard Penniman, was a pioneer of rock’n’roll, classing with the true greats of the genre.--- B is wrong because the adverbial modifier- comma and the present participle- point to Richard as the doer of the classifying act. This is a twist of meaning. Let’s drop it.
C) All agreed Richard, whose real name was Richard Penniman, was a pioneer of rock’n’roll, and classed with the true greats of the genre.--- and classed doesn’t sync --- drop
D) All who agreed Richard, whose real name was Richard Penniman, was a pioneer of rock’n’roll and classed with the true greats of the genre. --- This is a fragment; The unnecessary intrusion of that spoils the IC structure of the first clause
E) All agreeing Richard, whose real name was Richard Penniman, was a pioneer of rock’n’roll, classed with the true greats of the genre. This is also a fragment. There is no verb for the subject all.
Hope this helps.