The correct analysis of 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 in the 16th century, was designed to regulate trade and ensure that all vessels passing through the region obtained permission (a cartaz) from the Portuguese. This effectively allowed the Portuguese to exert control over maritime trade routes and disrupt the traditional trade networks that had previously existed among various local and regional traders. Therefore, this system marked a significant shift towards Portuguese dominance in the region.