Final answer:
The pardoner uses the tale of the three rioters as a moral lesson to instigate fear and persuade his audience to buy indulgences for salvation, thereby increasing his sales.
Step-by-step explanation:
The tale of the three rioters in 'The Pardoner's Tale' is a strategic narrative utilized by the pardoner to boost his sales. Through the tale, the pardoner warns of the vices that lead to the downfall of the three rioters and uses it as a cautionary parallel to his audience's potential fate if they don't repent and buy his indulgences. This tactic instills fear and encourages the listeners to purchase pardons to absolve themselves from sins, ultimately increasing the pardoner's profit.