Which statements about the sale of indulgences, a factor that led to the Protestant Reformation, are true? Choose all answers that are correct.
a. John Tetzel sold indulgences and kept the money for himself.
b. The Catholic Church taught that people could not avoid being punished for their sins.
c. Martin Luther believed the selling of indulgences was wrong.
d. An indulgence was an act of charity, a prayer, or a donation given in hope of a pardon for sins.