问题详情

The military officer was formally charged, because
A．he carried out the worst mass shooting in U.S. history.
B．he carried out the mass shooting at the U.S. largest military base.
C．he shot an army psychiatrist in a armed guard hospital.
D．he shot an unborn child being carried by a pregnant woman.请帮忙给出正确答案和分析，谢谢！