Which fort was built to promote trade with Native Americans in the Ohio Valley?

Fort Duquesne was constructed by the French in 1754 at the confluence of the Allegheny and Monongahela Rivers in the Ohio Valley. Its primary purpose was to secure French interests in the region and facilitate trade and relations with Native American tribes. The fort served as a strategic location for the French to control the vital fur trade and establish dominance over the area during the early conflicts leading up to the French and Indian War.

This fort's establishment was a direct response to British expansion efforts in the Ohio Valley, and it became pivotal in the struggle for control between the French and British empires. In contrast, the other forts listed were either part of different colonial conflicts or served other purposes. Fort Necessity, for example, was built by British forces in an attempt to establish a foothold in the region but ultimately was associated with early conflict, not long-term trade. Fort Pitt, while also significant, was constructed later, after Fort Duquesne had fallen into British hands. Fort Ticonderoga, located in New York, was important in different military campaigns but was not directly linked to trade in the Ohio Valley.