Why does the author mention the Sierra Nevada in line 12?A.To argue that a more direct rou
Why does the author mention the Sierra Nevada in line 12?
A.To argue that a more direct route to the West could have been taken.
B.To identify a historically significant mountain range in the West.
C.To point out the location of a serious train accident.
D.To give an example of an obstacle faced by the central pacific.