Which of Church's problems marriage of priest simony lay investiture do you think was the most harmful?

Among the issues faced by the Church, simony was particularly harmful as it undermined the integrity of the clergy and the spiritual mission of the Church. By allowing the purchase of church offices and privileges, simony eroded the moral authority of the institution, leading to widespread corruption. This practice not only diminished the value of spiritual leadership but also fueled public disillusionment with the Church, ultimately weakening its influence and credibility. In contrast, while issues like the marriage of priests and lay investiture were significant, simony directly compromised the Church's foundational principles.