Why did the railroads face labor shortages

The work was tiresome, as the railroad was built entirely by manual laborers who used to shovel 20 pounds of rock over 400 times a day. They had to face dangerous work conditions – accidental explosions, snow and rock avalanches, which killed hundreds of workers, not to mention frigid weather.

Explanation:

a. competition with other nations.

the correct answer is “opportunity cost”. opportunity cost is what a company misses out because it decided in one option over another one. in this case, the company decided to invest in building a factory so it gave up another possible benefit or profit in order to achieve success with the factory.  

trade-off is not the correct answer since it is a situation in which you accept losing something in return for benefits in other areas.

and finally, consequence is a general term used to accept what it comes when you make a decision. it can be a positive or negative consequence depending if the decision you took was the correct one.