What major event occurred in 1378 AD related to papal authority?

The papal authority experienced a significant crisis in 1378 AD known as the Papal Schism, which is the correct answer to the question. This event was characterized by a split within the Catholic Church where two, and later three, individuals simultaneously claimed to be the legitimate pope. The schism began shortly after the election of Pope Urban VI, whose controversial actions led discontented cardinals to elect a rival pope, Clement VII. This division created conflicting allegiances among nations and church leaders, severely undermining the church's authority and unity.

Understanding this event is crucial because it illustrates a pivotal moment in church history that raised questions about the legitimacy of papal authority and the governance of the Church. It set the stage for later reforms and contributed to tensions that would eventually lead to the Reformation. Other events mentioned in the options occurred at different times or were responses to different challenges, but the Papal Schism uniquely stands out as the key event in 1378 with respect to papal authority.