As Secretary of State, John Quincy Adams A. negotiated a treaty with Great Britain for Oregon Country.
B .made Manifest Destiny an official United States policy.
C. convinced Great Britain that it could not control Florida.
D. negotiated a treaty with Spain for control of Florida.

D. Negotiated a treaty with Spain for control of Florida.

Explanation:

In 1019 Adams had a brilliant diplomacy with Spain, which led to the Adams-Onís Treaty of 1819, was largely responsible for the Acquisition of Florida and the U.S. assumption of Spain's claim to the Oregon Country.

the answer is use of support