Why did Japanese soldiers kill so many civilians in Nanjing, China?

The best answer is B: commanders encouraged their soldiers to be as brutal as possible. During the Nanjing Massacre, Japanese troops committed widespread killings and other atrocities against civilians and prisoners of war; civilian attacks or battlefield panic do not explain the scale of the violence. This choice is a broad summary of the military culture and command failures that enabled the atrocities.

AI-written and checked against the verified answer.