Answer:
The correct answer is option C. Expansionists who favoured increased westward migration.
Step-by-step explanation:
These mountain explorers, who moslty lived near the Rocky Mountains, greatly contributed to the migration of colonists into the far West. They explored areas, opened up trails for the migrant colonists to pass and improved the roads for the wagon trains (a group of wagons) to head into the West. These trails and roads were also used to transport fur during the emerging and profitable fur trade.