Which of the following dependents is required to file a tax return?

Austin (17) earned $3,625 working at a local coffee shop. He also received $54 in interest on his savings account.

Roxie (19) is a full-time student at State College. She earned $5,525 working at a local grocery store.

Alex (15) earned $650 as a soccer referee. He is considered a contractor for all his referee income. He also earned $155 in bank interest.

Nora (59) is single and a dependent of her son, with whom she lives. In 2020, Nora had $320 in dividend income and $6,800 in earned income.