Final answer:
Option D, an autobiography with fictional elements, is the most clear example of Postmodern literature, characterized by genre blending and self-referential, metafictional elements.
Step-by-step explanation:
The most clear example of Postmodern literature would be Option D: An autobiography that introduces fictional elements. Postmodern literature is characterized by its rejection of traditional narrative structures and its blending of genres, playing with literary conventions, and including self-referential and metafictional elements. These tendencies towards narrative experimentation and a playfulness with literature's form and the idea of an 'author' align with works like Donald Barthelme's and David Foster Wallace's which utilize the experimental techniques of Modernists but are more playful and irreverent in nature.