Final answer:
Chapter 18 creates a framework story in Huckleberry Finn by exploring the theme of freedom and societal norms through the depiction of Huck and Jim's life on the raft.
Step-by-step explanation:
Chapter 18 creates a framework story in Huckleberry Finn because it introduces the theme of the river and nature as a symbol of freedom and escape. The chapter provides a detailed description of Huck and Jim's life on the raft, highlighting their desire to escape the constraints of society. However, the chapter also shows that the river is not separate from society, as it is connected to the social world on the shore. Through this framework, Mark Twain explores the tension between freedom and societal norms.