C. Only conclusion I follows
Feedback Conclusion I:
Disturbances in the society are due to people without self-discipline.We see that the question sentence states that discipline is key to ORDER in the society so people without discipline must be the source of the disturbance. Hence, it follows. Conclusion II:
There is nobody with self-discipline in the society.
There is no given statement in the argument about all the people in the society that points or establishes this fact. Thus this conclusion does not follow.
Hence, only I follows.