The correct answer is they blazed trails through the Rocky Mountains and other difficult terrain.
Mountain men were people who lived in the wild of Rocky Mountains from 1810 to 1880. These men played an important role in <em>creating roads</em> so people from the East could travel to the West, helping the fur companies improve their trade. Many mountain men worked as a <em>“free trappers”</em>(by their own), but a lot of them were hired by fur companies.
