The answer is Proclamation of 1763. It was issued by the British government after the French and Indian War and established a boundary line across the Appalachian Mountains, but it also had implications for the territories of the colonies. Specifically, the Proclamation allowed for the expansion of Georgia's southern border, enabling the colony to claim more land.
In contrast, the Treaty of Paris 1783 ended the American Revolutionary War and recognized U.S. independence, but it did not pertain specifically to the expansion of Georgia's borders. The Stamp Act and Sugar Act were primarily taxation measures and did not affect territorial boundaries.