I believe it is D, "France had recently regained control of Louisiana, and the United States wanted access to the port." Correct me if I'm wrong.
Answer:
The Louisiana purchase added more than 800,000 square miles of area to USA territory. This territory covered the area from the Mississippi River to Rocky mountains and from Mexico to the Canadian border. 15 new states were carved out from the Louisiana territory which includes the present-day states of Missouri, Nebraska, South Dakota, North Dakota. This purchase was important as the Americans were moving westwards since the 1780s into Ohio and Tennessee river valleys and for them the Mississippi River and the port of New Orleans was important. Thomas Jefferson was afraid that France under Napolean would try to dominate the Mississippi River and also the gulf of Mexico. The Mississippi River was important for western farmers as they used the river to transport their crops.
