Among the options provided, the most important tenet of Confucius is:
**b. Filial piety: devotion and service toward parents and ancestors and superiors.**
Confucius emphasized the importance of harmonious relationships within society, with filial piety being a key concept. He believed that by fulfilling one's duties and showing respect to one's parents, ancestors, and superiors, individuals could create a stable and prosperous society. While Confucius did advocate for wise and virtuous rulers, option (d) is an oversimplification and does not capture the essence of his teachings. Options (a) and (c) do not accurately represent Confucius' beliefs.