The key points of the exam are "the characteristics of school education in Tang Dynasty", which needs candidates' understanding. The famous teacher explained in detail that the school education in the Tang Dynasty was divided into two systems: official school and private school, with official school as the main one. The central official school is mainly "six schools and two libraries" These six schools refer to Guo Zi School, imperial academy School, No.4 School, Law School, Calligraphy School and Arithmetic School. They all belong to imperial academy and all have doctors to teach students. The second pavilion refers to Hong Wen Pavilion and Chongwen Pavilion. Among them, Hong Wen Pavilion belongs to the province under the door, Chongwen Pavilion belongs to the East Palace, and each has its own bachelor. The central official school mainly recruits officials' children, descendants of the royal family and international students, while the children of civilians in cloth clothes are only a few, which obviously reflects the hierarchical nature of education in feudal society. Therefore, the correct answer to this question is B.

The official school in Tang Dynasty was called "six schools and two halls". The Sixth School refers to imperial academy's Guo Zi School, imperial academy School, No.4 School, Law School, Calligraphy School and Arithmetic School, while the Second School refers to Hong Wen Hall and Chongwen Hall. This is the highest institution of learning in the Tang Dynasty, but Chongwen Pavilion was established in the 13th year of Zhenguan. In the 11th year of Zhenguan, there was only one Hong Wen Pavilion in Chang 'an.