PLEASE HELP ME!!

Read this passage from Part 1 of “The Purloined Letter.”

For one hour at least we had maintained a profound silence; while each, to any casual observer, might have seemed intently and exclusively occupied with the curling eddies of smoke that oppressed the atmosphere of the chamber. For myself, however, I was mentally discussing certain topics which had formed matter for conversation between us at an earlier period of the evening; I mean the affair of the Rue Morgue, and the mystery attending the murder of Marie Roget. I looked upon it, therefore, as something of a coincidence, when the door of our apartment was thrown open and admitted our old acquaintance, Monsieur G—, the Prefect of the Parisian police.

Which structural element is used in this passage?

The Purloined Letter, Part 1

flashback

scene

frame narrative (its not it i tried)

summary