Which South Korean singer/actress was a member of both DIA and I.O.I?
Jung Chae-yeon: Jung Chae-yeon (born December 1, 1997), better known by the mononym Chaeyeon, is a South Korean singer and actress. Jung Chae-yeon:  She is best known for being a member of the South Korean girl group DIA, and for finishing 7th in the survival show "Produce 101", making her a member of I.O.I. I.O.I:  The group was composed of eleven members chosen from a pool of 101 trainees from various entertainment companies: Lim Na-young, Kim Chung-ha, Kim Se-jeong, Jung Chae-yeon, Zhou Jieqiong, Kim So-hye, Yu Yeon-jung, Choi Yoo-jung, Kang Mi-na, Kim Do-yeon and Jeon So-mi.
Jung Chae-yeon