Eugenics and genocide  most often  are pursued in periods of increased internationalism and humanitarianism stable political, economic, and social environments periods of economic prosperity and rising standards of living unstable political, social, and economic environments

Eugenics and genocide most often are pursued in unstable political, social, and economic environments. Option D is correct.

Eugenics and genocide are most often found in times of economic uncertainty, for instance economic depressions, and in dictatorships,which constittute unstable political environments.  

Eugenics is a set of beliefs and practices that seek to enhance the genetic quality of a human population by excluding some genetic groups considered to be inferior.

could you go a bit more in depth with you question? it's quite hard to understand. as soon as you do that i will be glad to : )