117. Read the following passage, then answer the question below.

In 1957, the psychologist Leon Festinger proposed that people feel discomfort when they hold two beliefs, or a belief and an action, that conflict with each other, and that this discomfort, which he called cognitive dissonance, motivates them to reduce it. A smoker who knows that cigarettes cause cancer, for instance, may feel uneasy. Because quitting is hard, the smoker may instead decide that the evidence is exaggerated, or that a relative who smoked lived to ninety. The conflict disappears not because behavior changed but because belief did.

Festinger's most cited experiment, conducted with J. Merrill Carlsmith, illustrates the idea in a counterintuitive way. Participants spent an hour performing tedious tasks, such as turning pegs on a board. Afterward, they were asked to tell the next participant, who was waiting, that the tasks were enjoyable. Some were paid one dollar for this small lie; others were paid twenty. Later, when asked how enjoyable the tasks had really been, the group paid one dollar rated them higher than the group paid twenty. The explanation was that those who received twenty dollars had an adequate reason for lying, so they felt little conflict. Those who received a dollar lacked such a justification and, to avoid thinking of themselves as people who lie for nothing, convinced themselves that the tasks were not so bad.

Critics have pointed out that the original results were sensitive to details of the procedure, and later researchers have proposed that what matters is not inconsistency itself but a threat to one's self-image. Even so, the basic insight has proved durable. It helps explain why people defend decisions they have already made, why a group that has invested heavily in a cause is slow to abandon it, and why changing someone's mind with facts alone can be so difficult.

Why does the author mention a relative who lived to ninety?