The right answer for the question that is being asked and shown above is that: "B. expansion." A shortage of a natural resource can lead to which phase in the business cycle: It is the expansion stage of the business cycle.
The expansion of railroads directly led to economic growth in the us because more people were able to commute to and from their workplace to their homes. Since some work opportunities before railroads were seen as too far away from home, once the railroads were created and trains were running on the tracks, the lengthy distances were shortened and people were able to look for jobs in places where they were more abundant, therefore boosting the economy.
The rise of totalitarianism is one of the factor,as the totalitarian countries adopted expansionist policy thus causing threat to other nations, such as Germany’s frequent invasion, England finally declared war on Germany and wwii broke out
Another factor is the Great Depression,where American faced great economy problem and stop sending loans to other nations,it causes the economy situation to break down in Europe especially Germany. She needed a great sum of capital to rebuild her nation but at the time American stopped sending loans and demanded paying the dept,the economy of Germany then totally collasped,leading to the rise of totalitarianism which hostility finally cuased the wwii to broke out
hope it helps!