Why was Luther so worried about his own congregation in terms of indulgences

Luther didn't like the fact people could buy indulgences — or reduced punishment after death. ... Joel Hodge, from ACU's School of Theology, says the belief is that indulgences can reduce believers' need for purification from the effects of sin in Purgatory before they can enter heaven.

Explanation:

increases in demand are shown by a shift to the right in the demand curve. this could be caused by a number of factors, including a rise in income, a rise in the price of a substitute or a fall in the price of a complement.

which the answer is:

b