Answer
Zyklon B was a cyanide-based pesticide developed in 1922 by the German chemical company Degesch. It was originally used as a delousing agent to kill lice and fleas, but it was later adapted for use in the extermination of people in Nazi concentration camps during World War II. Zyklon B was used in gas chambers to kill millions of people, including Jews, Roma, homosexuals, and other political and religious prisoners.