Final answer:
Martin Luther challenged the Catholic Church due to objections regarding the selling of indulgences, taxation of ordinary Germans, and the delivery of Mass in Latin. He believed the Church had become corrupt and led the Protestant Reformation.
Step-by-step explanation:
Martin Luther challenged the Catholic Church due to several reasons. He objected to the Church's practices of selling indulgences, which were documents that absolved sinners of their sins. He also criticized the taxation of ordinary Germans by the Church and the delivery of Mass in Latin, which made it difficult for German Catholics to understand. Additionally, Luther believed that the Catholic Church had become corrupt and had strayed from the teachings of Jesus. His actions led to the Protestant Reformation.