Answer:
A. Spain
Explanation:
United States signed Adams-Onis Treaty with Spain by accepting the agreements made by both the nations. John Quincy Adams gave two proposals to Spain to opt for either of them. The first demand was to build control over East Florida and the other was to give it up to the United States. The option of giving up Florida to United States was agreed upon by Minister Onis and Secretary Adams . This treaty is also known as Transcontinental Treaty and was signed in 1819.
