Answer:
3.Prussia
Step-by-step explanation:
After the 30 years of war, Prussia managed acquired a territory of Pomerania. Since then, Russia manage the wet spot manage to expand its territory. They manage to expand their military influence through conquest and conducted one of the largest scale immigration in European history.
Both of these eventually contributed to the strengthening of the economy. The territory provided additional resources for Prussia and the immigrants provided large amounts of labors.