Answer:
Epiphany is a sudden revelation in a short story.
Irony is used in literature to lay emphasis on the story or a particular thing. It also involves the readers or audience to process the story on their own.
Situational irony is when what is happening in a particular scene is different from what is true or what the intended outcome is.
Explanation:
The term that is used to describe a sudden revelation in a short story is an epiphany. Epiphany is a sudden realization of or about something, that comes as a 'bolt' of understanding. It suddenly expresses or reveals the true nature of the character(s) through a particular word, or action or setting, etc.
Irony is the expression of a particular feeling or emotion but which signifies a completely different thing. This rhetorical device is used to express or show a feeling whose real meaning is the contrary of what was expressed. In literature, irony is used in such a way that it reveals the truth of a character or setting or scene which cannot be directly addressed or spoken by the characters. It also sometimes lays emphasis and provide a humorous tone to the story.
Situational irony is one such type of irony where the actions of the characters differ from what is happening. The outcome of the situation is the exact opposite of what was intended.