Which World Event Led to the First International Trial for Crimes

Which world event led to the first international trial for crimes against humanity?

A) The Nazi genocide of Jews and the murders of millions of others in concentration camps during World War II
B) The ethnic cleansing of Rohingya, a Muslim minority in majority-Buddhist Myanmar (also called Burma) , which has increased since 2012
C) The U.S. government's effort to outlaw the Ghost Dance among Plains tribes in the latter half of the 19th century
D) The Chinese government's persecution of practitioners of Falun Gong since 1999, including accusations of organ harvesting