Question

railroads not only led to an increase in the ability to transport raw materials, but they also led to a(n)
decrease in the need for raw materials.
increase in the demand for raw materials.
decrease in the uses of raw materials.
increase in the types of raw materials found in the united states.

Explanation:

Railroads improved transportation, making it easier to move raw materials. This would enable more production, thus increasing the demand for raw materials (since more can be used efficiently). A decrease in need/uses doesn't make sense as better transport supports more usage. Railroads don't create new raw material types, just improve transport. So the correct option is the one about increased demand.

Answer:

B. increase in the demand for raw materials.