Final answer:
The word that refers to 'a preface to an upcoming message' is a prologue. It introduces a story and provides a setting or background, unlike the epilogue which concludes the narrative.
Step-by-step explanation:
The word that means "a preface to an upcoming message" is c) Prologue. A prologue serves as an introduction to a story or a play, and it often provides background details or sets the scene for the narrative that is to follow. It is quite different from an epilogue which is found at the end of a literary work, often summarizing or bringing closure to the story.
For instance, in a book citation, if an author has written a preface, it would be included as part of the citation like this: Offill, Jenny. Preface. Mrs. Dalloway, by Virginia Woolf, Penguin Classics, 2021, pp. vii-xiv.
To contrast, an epigraph is a brief quotation found at the beginning of a literary work, such as the one by T.S. Eliot that precedes 'The Love Song of J. Alfred Prufrock', originating from Dante's Inferno.