The author includes excerpts from two versions of the story of Rapunzel primarily to show how the Grimms added details to make the story more vivid and engaging for readers. The Grimm Brothers revised their tale over several editions, transforming characters (like changing the fairy into a more sinister sorceress), adding dramatic and literary details, and disguising some of the original's more adult themes to appeal to a broader audience

. This comparison highlights the evolution of the story under the Grimms' authorship rather than merely retelling the story or showing cultural differences. Additionally, presenting two versions allows readers to see the changes made between earlier and later editions, illustrating how the tale became more informative and engaging over time

. This approach helps readers appreciate the development of the narrative and understand the plot and characters more fully, but the main purpose is to demonstrate the Grimms' editorial influence on the story's vividness and style

. Thus, the best-supported reason is: to show how the Grimms added details to make the story more vivid for readers.