Answer:
B. Their location on the Baltic Sea
Explanation:
Invasions from other powers had been taking place in the Baltic Nations for a very long time due to it's location.
I think its B but possibly C
Fertility rates and resources are connected because in areas where there are scarce resources and high fertility rates there will be problems in the ability to provide for the members of this hypothetical society. Therefore, individuals or animals could potentially live shorter and less healthy lives because of the lack of proper resources such as food, water, healthcare, or education.
It could help them if they pour a bottle of water on soil that has the max water it could hold they could find out just how Watered the ground is. Hope this helps!