The most accurate response that analyzes how the cartaz system represented a departure from previous patterns of trade is: "Portuguese ports now had exclusive control of Indian Ocean trade."
The cartaz system, implemented by the Portuguese in the Indian Ocean during the late 15th and early 16th centuries, required ships to obtain a license (cartaz) to trade, effectively allowing the Portuguese to exert control over maritime trade routes. This marked a significant shift from previous trading practices that were more decentralized and cooperative among various trading powers, such as Muslim and Venetian traders, who had previously dominated trade in the region.