Answer:
Option B
Step-by-step explanation:
Gold rush and mining opportunities in the west leads to Westward expansion during the 19th-century movement of people into the West,it was the construction of railroad lines that help facilitate this westward migration which brings people of all work of life to the west.The government helped westward expansion by granting right to railroad company which leads to the creation of the transcontinental railroad.The transcontinental railroad had a huge impact on the West and opened up this part of the country.
The abundance of iron in certain U.S. cities contributed to westward expansion in the construction of railroads.