Which of the Following Individuals Is in Kohlberg's Social System

Which of the following individuals is in Kohlberg's social system stage of moral reasoning?

A) Adam does his seatwork quietly because he knows that the teacher will send a note home if he doesn't, and then he will be punished.
B) Barbara tells the teacher all of the students who misbehaved while the teacher was away because she wants the teacher to always like her.
C) Clara does not think it is fair that she must miss recess; after all, she did what the teacher said to do, which was to quietly form a line by the door before the teacher counted to five. However, other students didn't and now the whole class suffers.
D) Don obeys the teacher because the rules of the school are that all students must obey the teacher. As a student he has a duty to obey.