Test analysis: According to the material information, "This is an era full of vitality and creativity, and this is also the era of the formation of ancient civilization in China", it can be judged that "this era" refers to the Spring and Autumn Period and the Warring States Period, and B is Mencius' proposition, which conforms to the meaning of the question; A and C are the viewpoints of Neo-Confucianism in Song and Ming Dynasties; Wei is Gu's thought.