what directly led to a population decrease in europe?\n○ invasions\n○ famines\n○ floods\n○ civil unrest

Answer:

B. famines

Brief Explanations:

Famines directly cause food shortages, leading to malnutrition, disease, and death, which directly reduces population. Invasions, floods, and civil unrest can also impact population but famines have a more direct and immediate impact on population decrease through starvation - related causes.