What British decree prohibited American colonists from settling west of the Appalachian Mountains?

The Proclamation Line of 1763 was a significant decree issued by the British government following the conclusion of the French and Indian War. Its primary purpose was to stabilize relations with Native American tribes by limiting the westward expansion of American colonists beyond the Appalachian Mountains. The British feared that unchecked settlement would lead to conflicts with Native Americans and the potential for further military expenditures to protect colonists.

This decree specifically prohibited colonial settlement in the newly acquired territories west of the Appalachians, aiming to prevent future hostilities and manage the integration of these lands into the British Empire. It also represented an early instance of colonial dissatisfaction with British governance, as many colonists viewed this restriction as an infringement on their rights and aspirations for land and economic opportunity.

The other options relate to different policies and acts that were part of the broader relationship and tensions between Britain and its colonies but do not pertain to the issue of westward expansion directly. The Stamp Act involved tax on paper goods, the Quartering Act required colonists to provide housing for British troops, and the Townshend Acts imposed taxes on various goods imported to the colonies.