The correct answer is peer interaction
One of the influential theories on moral development was presented by Lawrence Kohlberg, an American psychologist who lived between 1927 and 1987, and related moral development to the child's cognitive development.
He pointed out that through a maturational and interactive process, all people have the ability to reach full moral competence. In his main study, he interviewed 72 boys aged 10, 13 and 16 from around Chicago. He presented them with a series of moral dilemmas and they explained how they arrived at the solutions, and he came to accompany some of the subjects for about 20 years.
His theory has 3 levels of morality, each with 2 sub-stages.