The best answer to describe the most immediate impact of the Proclamation of 1763 on the British North American colonies is:
(Choice D) Colonists disobeyed the Proclamation of 1763, moving westward past the Appalachian Mountains.
The Proclamation was intended to stabilize relations with Native Americans and restrict colonial expansion westward, but many colonists ignored it and moved into the territory beyond the Appalachian Mountains.