GMAT Sentence Correction (SC) | Re: In 1791 Robert Carter III, one of the wealthiest plantation

349.In 1791 Robert Carter III, one of the wealthiest plantation owners in Virginia, stunned his family, friends, and neighbors by filing a deed of emancipation,setting free the more than 500 slaves who were legally considered his property.

(A) setting free the more than 500 slaves who were legally considered
(B) setting free more than the 500 slaves legally considered as
(C) and set free more than 500 slaves, who were legally considered as
(D) and set free more than the 500 slaves who were