Why did athens form the delian league

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.

Which of these was an accomplishment of the han dynasty? the invention of the seismograph finding a water passage to europe the invention of the ballpoint pen the invention of the abacus

What was the main cause of the russian revolution? a. the protests against the war with poland b. the tremendous war losses of world war 1 c. the protests against the treaty of brest- litovsk d. the losses dictated by the treaty of versailles