The correct answer is D) They relied on waterways like the Strait of Malacca to control important sea trade routes.
Geography most benefited the Malacca and Brunei sultanates in that they relied on waterways like the Strait of Malacca to control important sea trade routes.
In the sultanate times, these two islands represented an important place for trade and the passing of merchants and traders. Their closeness to Malaysia and Indonesia make those places strategict points in which different cultures and traditions converged. It was during the 15th century that the Sultanate exerted more power and control over the region.