Which of the following literary works is a collection of stories set in the Middle Ages?

The correct choice is a collection of stories set in the Middle Ages, and it is significantly known for its framing device of a storytelling contest among a group of pilgrims traveling to Canterbury. Written by Geoffrey Chaucer in the late 14th century, "The Canterbury Tales" features a variety of tales that reflect the lives, virtues, vices, and social conditions of its characters, who come from different social backgrounds. These narratives allow a vivid portrayal of medieval society, with themes that explore religion, love, morality, and the human condition, making it a cornerstone of English literature.

The other works mentioned do not fit this description: "Pride and Prejudice" by Jane Austen is set in the early 19th century and deals with themes of class and romance; "1984" by George Orwell is a dystopian novel set in a totalitarian future; and "Ulysses" by James Joyce is a modernist work that takes place in early 20th-century Dublin. Each of these works embodies different historical contexts and literary styles, distinct from the medieval setting of "The Canterbury Tales."