Which sentence gives the reader a clue that a flashback is beginning?

How does the author use the character of torvald helmer to explore a social use? -by revealing the changes that can happen to a person who has gotten wealthy quickly - by revealing attitudes related to spending and saving that men held during the victorian era -by revealing the bad financial advice that was given to many people in the victorian era -by revealing the hardships that fell on many people who lived during the victorian era