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

"Once Casper ducked inside, the four friends did the same but were soon confronted by a pack of angry dogs."

"Trace motioned for his friends to come close to him as he created a shield around them. He remembered the time when Tia had used her superpower to make the group invisible."

"Casper was obviously in disguise himself with his dyed brown hair and beard. The last thing the group needed was for Casper to realize that he had been spotted by his nemesis."

"Casper was leaving the pet store and getting into a car, so the friends hurried to their car."
Question 2
Part B

How does the flashback in Part A affect the story?

It shows how the group first met.

It reveals that Tia is also a superhero.

It uncovers Casper’s secret power.

It tells the story of Trace’s background.