Which was a difficult the builders of the transcontinental railroad had to overcome?

Which of the following is an example of the pull factor known as economic migration? a. better educational opportunities pulling people towards a new country b. mexican laborers entering the us to work in agricultural jobs c. joining family members that are already in a new country d. crop failures driving people away from their country i am unsure on this question, i was thinking b? but i could be wrong.

An alliance of two political parties is know as? a. majority b. coalition c. candidate d. government

The low and midlevel clouds that look like cotton balls are