According to the passage, Alpers and Schwartz disagree about which one of the following? A. the degree of control Rembrandt exercised over the production of his art B. the role that Rembrandt played in organizing professional brotherhoods and academies C. the kinds of relationships Rembrandt had with his students D. the degree of Rembrandt's involvement in the patronage system E. the role of the patronage system in seventeenth-century Holland