The correct answer is A. Between 1812 and 1821, the United States purchased the Florida Territory from Spain and seven states were admitted into the Union.
Florida was transferred from Spain to the United States for $5 million, with the signing of the Adams-Onis Treaty in 1821.
In turn, the 7 new states that joined the Union were:
-Louisiana (April 30, 1812)
-Indiana (December 11, 1816)
-Mississippi (December 10, 1817)
-Illinois (December 3, 1818)
-Alabama (December 14, 1819)
-Maine (March 16, 1820)
-Missouri (August 10, 1821)