Spain sold florida in 1819 to the united states because it
a. received america's promise to give up claims to oregon.
b. thought the sale of florida might stop american settlers and frontiersmen from further pushing into texas and other parts of spain's holdings in the southwest.
c. was pulling out of the western hemisphere.
d. wanted to america to become a rival to britain.
e. could not defend the area and would lose it in any case.