Answer:
The correct answer is B) Other country's possessions
Step-by-step explanation:
By then 19th century, America was still a very small country compared to modern borders. However, many American politicians believed in a 'Manifest Destiny' in order to expand the country from coast to coast.
Small frontier settlements as far as California already existed and the idea was encompass all of the land between Canada in the north and Mexico in the South.
However, the major obstacle for this were the various North American possessions of other countries.
One example was of Louisiana, a part of land in North America owned by the French Empire. At the time, this was larger than the rest of the United States. Eventually the French agreed to sell it.
Spain was another major land holder in North America including the large possession of Florida.