Final answer:
Proximity to a seaport was vital for Roman trade because it provided a cost-effective way of transporting goods and enabled the Roman economy to flourish by facilitating imports and exports.
Step-by-step explanation:
Proximity to a seaport was important to Roman trade primarily because shipping by sea was less expensive than transportation by land. The Roman economy thrived on the efficient movement of goods around the vast Mediterranean empire, and having access to a seaport facilitated this process. While the Romans constructed an extensive network of roads, it was the seaports like Ostia that played a crucial role in trade. These ports allowed Rome to export products produced in Italy and to import luxury goods and necessary items such as grain, wine, and olive oil, which were often transported in sturdy containers called amphorae. The integration of road and sea routes bolstered the economy and enabled the collection of taxes, which funded public works and government programs, ensuring the functioning of the Roman economic system.