an economic impact of the black death was a labor shortage. This resulted in a shift in power, away from landholding nobles and towards 

The new millennium brought other challenges to the Black Death—bubonic plague link, ... plague through painstaking analysis of the Black Death's movement and ... was intended to eliminate doubt but inability to replicate initially positive results ... arable production in favor of sheep—raising, which required far less labor.

Explanation:

i believe it d) heterogeneous

the term is einsatzgruppen