How did railroad expansion lead to industrial growth

Because if you got more resources to the construction of the factory it could be built faster so when the factory was built half of the money.Will go to the boat company and railway that got the recourse to the factory.Also you have to look at the supply and demand if they wanted more dresser the demand for.More recourse so the railroad company will give them recourse.And this also helped with the workers coming from the country side to work it was 2$ a week but its more from where they worked in the fields.   

Ibelieve the answer is answer 5