The Louisiana Purchase of 1803

A. Was a major cause of the Spanish-American War.
B. Resulted in increased conflict between the U.S. and France.
C. Resulted in the removal of all British military forces from North America.
D. Almost double the area of the U.S. and gave it control of the Mississippi River.

It is D, almost double the area of the U.S. and gave it control of the Mississippi River. Have a nice day!