Why Did the Church Impose Such Harsh Sanctions on Heretics

Why did the church impose such harsh sanctions on heretics who refused to repent of their allegedly false beliefs?

A) Church leaders believed that burning heretics at the stake would save the souls of those sinners.
B) Church leaders believed that unrepentant heretics jeopardized the souls of those around them.
C) Church leaders believed that unrepentant heretics were likely to forge an alliance with other enemies of the faith, including Jews and Muslims.
D) Church leaders thought that unrepentant heretics could be enlisted by ambitious political rulers such as Frederick Barbarossa who had clashed with ecclesiastical authorities.