Answer:
The French got Senegal in Africa which helped it to gain monopoly over slave trade from Africa.
So, option D is the right answer.
Step-by-step explanation:
The France had lost all its territories in North America, in the Seven Years wars (1756 - 1763) because of the British. So, it wanted to take revenge and weaken the British. France started helping the American Revolutionary war in 1775.
In 1776, Benjamin Franklin visited France seeking its support. In 1778, a treaty was signed between U.S and France by which France supplied money and arms to the United States. France help was so crucial for U.S because it lacked arms and allies and ultimately, it helped the U.S to gain independence from British. But France accumulated debt because of the costs incurred during its participation in the war.
During the war, France conquered several areas in the Caribbean islands but returned them all except the Tobago, which was a fertile area. After the war, France got Senegal in Africa, which was an important slave trading station, and hence France got a monopoly on the slave trade from Africa. Hence, option D is the correct answer.