What practice of the Roman Catholic Church is Martin Luther calling into question in his 95 Theses?

Question

Responses
A The practice of penance for the forgiveness of one's sin.The practice of penance for the forgiveness of one's sin.
B The practice of confession as a way of absolving one's sin.The practice of confession as a way of absolving one's sin.
C The selling of indulgences to grant forgiveness rather than granting forgiveness through penance.The selling of indulgences to grant forgiveness rather than granting forgiveness through penance.
D The practice of helping the poor and needy for personal gain rather than because it is the right thing to do.

Answer 1

C The selling of indulgences to grant forgiveness rather than granting forgiveness through penance.