Answer:
The clearest example of metafiction is story C. A story with footnotes that comment on the author's process.
There are many resources that can be employed to make use of metafiction (a narrative technique in which the author constantly reminds the reader that he or she is reading a fictional work), and some of them include:
 Telling a story within a story
 Telling a story about a third person who's reading or writing a book
 And of course, telling a story and making use of footnotes to comment on it 
In this way the reader is engaged and becomes a participant in the story, forcing himself to think about the nature of the narration and how much credibility exists in the stories he/she reads.
Step-by-step explanation: