Which of the following is the best example of a frame narrative?

a. barnyard animals conspire to overthrow the humans on the farm and start their own government.

b. a boxer tries to put himself in the mind-set of his opponent, but his dislike for the man overcomes his empathy.

c. a detective discovers that the kidnapper she's been investigating is actually her other personality.

d. four survivors of world war ii sit around a table and share their war stories with a naïve reporter.