Which of the following defined the role of bishops in ecumenical councils?

The option that indicates bishops are tasked with maintaining unity and doctrinal purity is correct because ecumenical councils were established to address significant theological issues and disputes within the Church. Bishops, as the leadership of the Church, play a crucial role in these councils by representing their local congregations and ensuring that the teachings and practices align with orthodox beliefs.

Throughout the history of the Church, bishops have met in councils to discuss and clarify doctrinal matters, create guidelines for Christian living, and resolve conflicts. Their participation is critical for fostering consensus and safeguarding the unity of the Christian faith against heretical interpretations. This responsibility underscores the bishops' role as stewards of doctrine and guardians of ecclesiastical unity, highlighting their authority in the broader context of the Church rather than merely local oversight or independent governance.