Which advance accelerated the settlement of western regions of the united states and canada during the nineteenth century

Construction of transcontinental railroads accelerated the settlements of western regions of the United States and Canada during the nineteenth century.

Explanation:

Transcontinental railroads were famous not only for their magnificence but it developed physical link between the west and the eastern countries. It established easy movement of goods which in a way compelled the people to settle along the west of United States.  

The sellers had found new openings in the market to sell their goods and they found buyers who could buy their commodities internationally. Many towns sprung up along the business route and many families were able to travel easily due to the road systems. It also played a vital role during the war times too.

answer; /// (c) i do believe that the correct answer is ; an unstated guarantee that goods will be to the consumer's liking;