Alcohol & Drugs: MIP, MIC, Intoxication very confusing

[CARAMIa]

Does anyone know if an 18 year old in Calif can get contributing to a minor I was told by a friend her son was pulled over and told since he was in a car where beer was in the trunck and he was 18 and there were 17 year old's in the car he would get a minor in possecion charge plus contributing to a minor very confussing is he a minor or an adult contributing