Final answer:
The Appalachian Mountains acted as a barrier to colonization, directing settlers to move south along the coast instead of westward due to the Proclamation of 1763 which forbade settlement west of the mountains, thus contributing to the tensions leading to the American Revolution.
Step-by-step explanation:
The impact of the Appalachian Mountains on colonization can be best described as a barrier that influenced settlement patterns. Answer B is the correct option: The Appalachians formed a barrier for colonization; therefore, the colonies did not extend west, but south along the coast. After the Seven Years' War, the British government issued the Proclamation of 1763 which forbade colonists from settling west of the Appalachian Mountains in an effort to prevent conflict with Native American tribes and avoid the costs of defending the frontier. The colonists saw this as an act of tyranny, and it was a factor that added to the growing tensions between Britain and the American colonies, contributing to the eventual American Revolution.
Colonists, eager to expand and with a growing need for new land due to population growth and exhausted agricultural lands, saw the land west of the Appalachians as a promise for future prosperity. However, the British proclamation and the physical barrier itself directed colonization along the coast and southward, rather than westward expansion.