Which of the following statements is true about a story's narrator?

the narrator is usually the author so that he or she can tell you what all of the characters are thinking or feeling at any time.
the narrator controls what information your reader receives about events in the story and what the characters are thinking.
the narrator is usually one of the characters in the story who knows everything about what the others are thinking and feeling.
the narrator controls only the information that the main character is aware of and so is limited by that character's experiences.