The correct answer is amending the Constitution.
In Article V of the US Constitution, it discusses how there needs to be a 2/3rds vote in both the House of Representatives and the Senate. Along with this, the possible amendment needs to be ratified (aka approved) by at least 3/4ths of the states within the US. If both of these requirements are met, then the bill becomes an amendment.
Both men believed that the Catholic Church should end the sale of indulgences. Option C is correct.
An indulgence is a pardon for certain types of sin. The Catholic Church sold indulgences in the late medieval period, and their sale motivated Martin Luther to present his "95 Theses, "which was a document created in 1517 to attack the Catholic Church’s corrupt practice of selling “indulgences” to absolve sin.