The correct answer is the Holocaust.
The Holocaust is also known as Shoah. It was a genocide during World War II in which Nazi Germany murdered some six million European Jews between 1941 and 1945.
Nazi Germany persecuted and murdered Jews, Slavs, the Roma, the sick and the disabled, and the political dissidents.
The total number of all Holocaust victims is estimated at over 17 million.
The term holocaust comes from Greek and means 'burnt offering'.