Question

what event marks the beginning of systematic mass murder of the jewish people in nazi - controlled territory?
an order of hermann goering to reinhard heydrich just after the invasion of the soviet union
the wannsee conference
an internal memo of adolf hitler to heinrich himmler in nuremberg
the opening of the dachau concentration camp in 1933

Explanation:

After the invasion of the Soviet Union, Hermann Göring gave Reinhard Heydrich an order. This order was crucial as it set in motion the systematic mass - murder of Jews in Nazi - controlled territory. The Wannsee Conference (1942) was about the "Final Solution" implementation details but not the start. The Dachau camp opening (1933) was early persecution, not the start of systematic mass - murder. There is no such internal memo of Hitler to Himmler in Nuremberg related to this as the start.

Answer:

An order of Hermann Goering to Reinhard Heydrich just after the invasion of the Soviet Union