The Protestant Reformation began in the early 1500s as a reaction to some of the practices of the Catholic Church. What was one of the main consequences of the efforts of reformers such as Martin Luther?"

A.
The power of the nobility was increased.
B.
The ideas of the Renaissance were expanded.
C.
The principles of Humanism were advanced.
D.
The authority of the pope was challenged.

D. The authority of the pope was challenged.