By revealing the clergy's vindictive abuse of power.
Explanation:
Geoffrey Chaucer's "The Canterbury Tales" is a collection of stories told by a group of pilgrims on their way to Canterbury. The given excerpt is from "Prologue to the Pardoner's Tale" where the clergy talks of his 'job' of pardoning people but as a means to profit from them.
In the given excerpt, the pardoner reveals how he used his clergy position to 'attack' those who criticize him. His victims <em>"can't escape slander and defamation"</em>, which he admits is <em>"how [he] deals with people who annoy [him]"</em>. This reveals how the pardoner used the guise of being holy and virtuous to attack his enemies or anyone criticizing him. This shows the vindictive abuse of power by the clergy.