Answer:
not 100% sure but I think its the first one, the west benefited from increased travel an tourism.
Explanation:
before the rail road it was very hard to get to the west,( extreme weather, raiding natives, scarce food etc.) but still many people wanted to see the west. the rail road provided a solution to most of the problems with traveling. and people jumped on (get it) the opportunity.
The correct answer is - natural selection.
This is a typical case of natural selection, where we have a group of people that have similar physical traits, that are selected and than isolated from any external influence, so with interbreeding they manage to keep their physical traits for generations to come and thus create a population that resembles their initial ancestors.
<span> it is <span>mountain men hope i helped
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