Which scenario is the best example of a frame narrative?

A frame narrative is a literary technique which presents a story within a story, where a main narrative is presented in prder to introduce a more emphasized second narrative or a collection of short stories.
Of the four scenarios presented, the best example of a frame narrative is C. Four survivors of World War II sit around a table and share their war stories with a naive reporter. That premise is an exact representation of a story (or a series of short stories) within a story.