Answer:
They worked in dangerous conditions.
For the first one i think the answers are A, B and D
I'm not sure about the second one tho, but i guessing its either B or C
Hope this helped :)
John Fremont's ability to draw accurate maps was a talent. The map of the Great Basin was what "changed the entire picture of the West". His maps after 3 expeditions were used by thousands of people moving West.