Why was Thomas Beckett killed at Canturbury Catherdral?    aHe appointed his brother as a priest bThe king's loyal knights heard the king say he was angry at him cHe was a dishonest priest and stole money from the church dHe angered the king by calling him ugly

Thomas Beckett was killed at Canterbury Cathedral because of option b. The king's loyal knights heard the king say he was angry at him. This happened because Beckett, who was the Archbishop of Canterbury, had a series of conflicts with King Henry II of England over the rights and privileges of the Church. This led to a breakdown in their relationship. When the knights heard King Henry II utter in frustration, "Who will rid me of this turbulent priest?", they took it as a royal command and murdered Beckett in the cathedral.