D.J. Tanner’s younger sister played by Jodie Sweetin is named Stephanie.
Stephanie Judith Tanner is the middle Tanner daughter, between D.J. and Michelle. Jodie Sweetin played Stephanie throughout Full House, beginning when she was a child performer and continuing through the series’ eight-season run. The character is known for her quick wit, curiosity, and recurring catchphrase, “How rude!”
Stephanie’s position in the family is a frequent source of storylines. She is younger than D.J., the oldest Tanner sister, but older than Michelle, the youngest. That middle-child role lets the show explore both sibling rivalry and Stephanie’s attempts to assert independence as she grows up.
The other options refer to different characters: Gia Mahan is Stephanie’s friend and later romantic interest, Kimmy Gibbler is D.J.’s best friend, and Michelle is Stephanie’s younger sister. Jodie Sweetin is specifically associated with Stephanie, while Mary-Kate and Ashley Olsen shared the role of Michelle.