By revealing important events in a character's past.
Explanation:
Flashbacks help us understand characters more and build on characters' personalities. They help us understand why they do certain things and what has led up to their current decisions. I guess it could be number three, but the first answer is the most obvious and logical one.
Answer: By revealing important events in a characters' past.
Explanation: Flashbacks are moments in which the author goes back to the character's past and they help explain the reasons or the motivation a character has to do certain thing. The answer could also be the third one, but you can also accomplish the third one without using flashbacks, so, the correct answer is the first one.
