Final answer:
Henry IV was the most in favor of lay investiture. Pope Gregory VII banned simony, but Henry IV continued the practice, leading to a conflict with the pope.
Step-by-step explanation:
The most in favor of lay investiture was the investiture controversy was a power struggle between the Catholic Church and secular rulers over the appointment of bishops and other Church officials. Pope Gregory VII banned the practice of simony, where kings appointed officials in exchange for bribes. When Henry IV continued to appoint officials, Pope Gregory VII excommunicated him and declared his rule illegitimate. This led to a rebellion against Henry IV by German princes, and the pope gained more power over the appointment of Church officials.