Why is filial piety the "source of all virtues" in Confucianism?

A. because Confucius believed it is the model for the other four relationships

B. because Confucius believed soldiers should be honored for their duty above the family

C. because Confucius believed equality in relationships was the basis for the other four relationships

D. because Confucius believed people should behave properly in order to avoid punishments

I already answered this question but here it goes again:

The correct answer is A because of the following reasons:

- Confucianism always compares a family to society. It considers that just as a father is the head of the family, an Emperor is the head of the State. The mother is like the Empress and the siblings are like the different classes of society. In this manner, not only your close relatives are your brothers (and sisters), your fellow subjects are also your relatives of a much larger family, society. If both the family and society is to function well and be happy and prosperous they need to care and protect one another. Because the model of the immediate family is the model of reference for all the other types of relationships, filial piety occupies a central place not only in Confucianism but in Chinese culture as well.