The correct option is A
The Treaty of Adams-Onis or Treaty of Transcontinentality of 1819-1821 was the result of the negotiation between Spain and the United States to fix the border between the North American nation and the then viceroyalty of New Spain.
The border was set beyond the Sabina River and Arkansas to the 42nd parallel north. As a result, Spain renounced its possessions beyond that latitude, including the territory of Oregon. It also ceded definitively the Floridas, the Louisiana and the navigation by the Mississippi river. The Spanish Crown remained the sole sovereign of Texas, territory that the United States claimed as part of Louisiana, which was purchased from the French in 1803.
The treaty was beneficial for both parties. In the case of Spain, it received the sovereignty of Texas in exchange for sovereignty, which it de facto did not have, in Florida. In addition, the territories of the Oregon were very remote and without any commercial value. The United States won its transcontinentality, Florida and the territory without defined borders of Oregon, which would be a matter in dispute with the British installed in Canada.
