Final answer:
The Santa Fe Trail was primarily used for trade with the local inhabitants of the Southwest, rather than being a route for American settlers traveling to California. therefore, option A is correct
Step-by-step explanation:
The Santa Fe Trail was primarily used for trade in the beginning, so the correct answer to your question is A. to carry on trade with the local inhabitants of the Southwest. It played a significant role in the commercial and economic expansion of the United States, facilitating the exchange of goods between the Missouri frontier and the Mexican frontier. The Santa Fe Trail was not initially used to bring American settlers to California; that was the purpose of the California Trail.