Answer
The Reichssicherheitshauptamt (RSHA), led by Ernst Kaltenbrunner, encompassed three primary offices crucial to Nazi Germany's security apparatus: the Gestapo (Secret State Police), Kripo (Criminal Police), and SD (Security Service). These entities collaborated to enforce ideological conformity, suppress dissent, gather intelligence, and carry out heinous acts such as the Holocaust, making the RSHA a central instrument of Nazi tyranny.