Final answer:
The group of people gather at the Tabard Inn to hold a storytelling competition during their pilgrimage, as depicted in Geoffrey Chaucer's The Canterbury Tales. Option b is the answer.
Step-by-step explanation:
The primary reason for the group of people gathering at the Tabard Inn is b) To hold a storytelling competition. This setting is featured in Geoffrey Chaucer's The Canterbury Tales, where a diverse group of pilgrims meet at the inn and decide to tell stories to pass the time on their journey to the shrine of Saint Thomas Becket in Canterbury. The storytelling becomes a friendly competition, with the prize being a free meal at the inn upon their return.