What Distinguishes the Holocaust from Other Episodes of Genocide in History

What distinguishes the Holocaust from other episodes of genocide in history?

A) Those killed included large numbers of women and children.
B) The perpetrators left behind little paperwork or physical evidence of the killings.
C) The perpetrators did not rely on the prejudice of the local populations.
D) The killings were systematized and deliberately planned.
E) The killings were concentrated in one area, rather than a large network of camps.