When Do Historians Believe Hitler Lost Any Remaining Hesitation About

When do historians believe Hitler lost any remaining hesitation about implementing his long-held ambition to exterminate the Jews?

A) after Germany lost its first significant battle
B) in the 1930s, several years before the war began
C) as German forces advanced into the Soviet Union
D) when the United States entered the war
E) when Hitler began showing signs of insanity