Final answer:
The transfer of Florida from British possession back to Spain occurred due to the Adams-Onís Treaty of 1819, following General Andrew Jackson's military actions in Spanish Florida. The treaty resolved territorial disputes and led to future American expansion.
Step-by-step explanation:
The event that transferred Florida from British possession back to Spain in the late 1700s was not mentioned explicitly, but the late 1700s context points towards the Treaty of Paris of 1783. This is not one of the options provided by the student, which appears to focus on the early 1800s events. However, if we consider the time frame given in the question as approximate and refer to the early 1800s, the transfer of Florida back to Spain actually occurred as a result of the Adams-Onís Treaty concluded in 1819, after a series of events involving General Andrew Jackson's incursions into Spanish Florida.
This treaty not only ceded Florida to the United States but also defined the border between the United States and New Spain, effectively drawing a line for future expansion. As a part of this agreement, the U.S. relinquished claims to parts of the west, and Spain forgave a $5 million debt. The conditions laid out ushered in new territorial configurations and opened the way for American westward expansion.