An author's use of foreshadowing the reader form about the story.

inferences
predictions
references
theories

The correct answer is: predictions

Foreshadowing refers to a literary device used to give the reader an advance hint of what is going to happen later in the story. It is found, most of times, at the beginning of the story, or of a chapter helping the reader to develop expectations about the events coming. This device is udeful in creating an atmosphere of suspense, oncreasing the reader's interest. In a mystery novel the author can use foreshadowing to give a clue about a murder that will take place.

In that way we know that the reader forms predictions about the story as several clues are given to him to catch his attention.  

It is a fact that supports the main idea.