What idea is more conceptual than concrete

the answer is D because no one can really have a boundary

confucius was a great thinker and teacher, and philosopher succeeded in laying the foundations beloved.

he many principles but waht   was speak about the relationships was the third .

the third important concept , the real man's idea. he is the man who lives up to the highest moral standards. man shows five virtues: in self, generosity, sincerity, perseverance, and benevolence. his relationship is described as follows: when a son is always loyal, as a father is just and gentle, as an administrator is loyal and loyal, and as a husband is honest and fair, and as a friend, he is faithful and languid. if everything is a true happiness conference, justice and harmony will rule the empire.