D) Stephen F. Austin
Along with the rest of Mexico, Texas gained its independence from Spain in 1821 following the Treaty of Córdoba, and the new Mexican state was organized under the Plan of Iguala, which created Mexico as a constitutional monarchy under its first Emperor Agustín de Iturbide. During the transition from a Spanish territory to part of the independent country of Mexico, Stephen F. Austin led a group of American settlers known as the Old Three Hundred, who negotiated the right to settle in Texas with the Spanish Royal governor of the territory.
