What term best describes twain's exploration of social-class structure in the adventures of huckleberry finn? inferred meaning figure of speech theme understatement

The correct answer here is the third option.

Theme would be the term that would best describe Twain's exploration of social class structure, as it is exactly through the theme of The Adventures of Huckleberry Finn that he explores. One of the major themes of the works is the social-class in the work and it is explored through many characters, such as Jim who is a runaway slave, Grangerfords who are the elite, various common folk and so on.