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.