Final answer:
Britain divided Florida into East and West Florida because it was too large to govern as one colony, not due to external requirements from the Treaty of Paris or pressure from France and Spain.
Step-by-step explanation:
After the conclusion of the French and Indian War, Great Britain gained vast territories, including Florida, which had been under Spanish control. The correct explanation for why Britain divided Florida into two colonies is that Britain felt that Florida was too large to govern as one colony, so it formed East and West Florida. This division was not stipulated by the 1763 Treaty of Paris, nor was it a requirement imposed by France or Spain. The division allowed Britain to manage the territory more effectively by establishing smaller, more manageable administrative units.