According to the options stated, the one that is correct is letter C: “Twain's choice of this river for the setting adds a sense of adventure and also makes the novel seem believable”.
“The Adventures of Tom Sawyer” takes place in St. Petersburg, Missouri, along the Mississippi River, in the 1840s. Although Tom Sawyer critiques much of American society in this seemingly light-hearted set of adventures, the small town and surrounding area is Tom’s playground for all the adventures he goes through in the novel.