Which European country does Prussia have a rivalry with?

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.

What former head of the cuban secret service was charged with protecting the country's prime minister for nearly 50 years?

Which events are correlated but do not necessarily have a causal relationship?