B is the best answer. The author's argument concerning the effect of the official sale of duplicate artifacts on illegal excavation appears in lines 74-75, in which the author predicts that such official sale would reduce demand for “the clandestine product.” The rhetorical question that follows (lines 76-80) indicates that the author finds it unlikely that any purchaser would prefer objects of unknown provenance to objects of known origin, or, to rephrase, the author assumes that most people would prefer to purchase objects of authenticated provenance, as this choice states.