The assertion that best correlates Roman expansion policy with trade in the Indian Ocean is:
"As the Romans conquered territory, they gained access to trade resources, which encouraged more expansion."
This choice highlights a direct relationship between territorial conquest and the acquisition of valuable trade resources, which in turn facilitated further expansion. Roman expansion was often motivated by the desire to secure trade routes and resources, particularly spices and luxury goods from regions connected to the Indian Ocean trade network.
Other responses suggest various perspectives, with some indicating a lack of correlation or emphasizing punishment for non-compliant civilizations. However, these views neglect the broader economic motivations that were central to Roman imperial policy. Moreover, while the spread of religion was a factor in Roman expansion, it was generally secondary to economic interests, especially in the context of trade.
Overall, the chosen response encompasses the multifaceted motivations behind Roman expansion, particularly the importance of trade access and resources in driving further conquests.