If the options are:
A.It sets up an expectation that exempla, which were common in didactic medieval literature, will be part of the story.
B.It allows Chaucer to write his poem in English because he is capturing the speech of English commoners.
C.It provides Chaucer with an opportunity to write about characters that represent a wide range of social classes.
D.It makes the messages of the pilgrims more persuasive because a reader in Chaucer’s time would have respected them for their fervent religious beliefs.
I believe the most important effect is C. Pilgrimage was an important event in the lives of all people who could do it, so it happened on the widest social scale. There are priests, monks, friars, but also people from the lowest class, such as peasants. They meet and talk, but they are also heroes of the stories. The action begins in a tavern, which was the most democratic place at the time, where members of all social classes could meet and talk.
