The correct answer is: "receiving money for the remission of sins".
The Catholic Church used to sell indulgences. Extremely poor people spent all the money they could have saved to buy these products, because they were told in church (and therefore they believed so) that they would be forggiven for their sins and heaven would await for them after the purchase.
Martin Luther criticized the existence of this lucrative activity connected to the power of removing sins, which according to his beliefs was only held by Gold. Therefore, the members of the clergy were deceiving their congregations just to earn money for themselves.
Out of the choices given, the one Martin Luther most strongly criticizes in his Ninety-Five Theses are forcing young girls to become nuns, and receiving money for the remission of sins. The correct answer is A.
