The correct answer is D. The systematic mass slaughter of European Jews and and others in nazi concentration camps during world war II.
Explanation
The Holocaust was the mass murder of millions of people by the Nazi regime during World War II (1939 and 1945). During this period there was a radical persecution campaign against those considered as ‘inferior’ as the Nazis believed only the Aryan race should prevail and others should disappear, this included not only the Jewish population, but also gypsies, the disabled, Jehovah's Witnesses, homosexuals, and communists. Under this ideology, the Nazis created concentration camps and gas chambers that lead to mass murder through poor living conditions and asphyxiation by gas inhalation and many other laws and actions to end with those that were not considered fit for society. So, the correct anwer is D. The systematic mass slaughter of European Jews and and others in nazi concentration camps during world war II.
Nevertheless the Holy Roman Empire kept alive the idea of a unified Europe by maintaining a connection with Rome and the Kingdom of Charlemagne. Napoleon has come closer than anyone to unifying the European continent.
