Part A Which sentence from "Superhero 101: A Dog's Day" indicates a flashback?

"Blade immediately noticed Trace’s countenance and followed his gaze."

"They followed him to an abandoned pet food manufacturing plant at the edge of town."

"Trace was still thinking about the conversation with his grandmother when he stopped so abruptly that Liam literally collided with him."

"'Look, over there. It's Casper. He’s supposed to be in prison.'"
Question 2
Part B

How does the flashback in Part A affect the story?

It introduces another character to the story.

It shows how profoundly Trace's grandmother's revelation affected him.

It shows the readers how the team works together.

It reveals where Casper has been hiding.