Final answer:
Political conflicts and the Avignon Papacy weakened the power of the papacy in western Europe in the fourteenth century. The move of the papacy to Avignon, coupled with the Great Western Schism and the rise of secular nation-states, undermined papal authority and prestige.
Step-by-step explanation:
The events that weakened the power of the papacy in western Europe in the fourteenth century were primarily related to political conflicts and the Avignon Papacy. The tension escalated between Pope Boniface VIII and King Philip IV of France, which resulted in a significant weakening of papal authority. The subsequent move of the papacy to Avignon, known as the Avignon Papacy, further diminished the pope's spiritual prestige as seven popes resided in France, appearing to be under the control of the French king. This situation led to two competing papal courts for nearly sixty years, which exacerbated the crises of authority and instigated the Great Western Schism. Additionally, rising secular powers in the form of nation-states were keen to reduce papal influence to consolidate their own power. Therefore, the correct answer to the question about what events weakened the power of the papacy in the fourteenth century is 'c) Political conflicts and the Avignon Papacy.'