Tommy, a 14 year-old boy, makes his moral decisions based on how they fit in withconform to the rules of his group of friends. into which stage of development would kohlberg place tommy?

The answer to this question is Conventional stage
In kohlberg's development theory, Morality that people had during conventional stage relies solely on what our social group tell us to believe.
During this stage, people tend to not fully understand the complexity of each principles and only follow a certain morality view just to be accepted