The answer is a short story.
It is not tragedy because tragedy uses dialogues and emotions and not narration.
It is not a lyric poem because these express emotions and feelings and don't use narration.
It is not an expository essay because this is a genre of writing that is explaining something to the reader.
Therefore it is a short story which is an invented prose narrative shorter than a novel usually dealing with a few characters and concentrating on the creation of mood rather than plot.
