The correct statement regarding the social structure of Tang and Song China compared to feudal Europe is:
It allowed for more social mobility based on merit.
In Tang and Song China, the civil service examination system provided a pathway for individuals to enter the bureaucracy based on merit rather than solely on aristocratic birth. This system enabled men (and, to a lesser extent, women in certain circumstances) of lower social status to gain prestigious government positions through education and examination.
In contrast, feudal Europe was characterized by a more rigid social hierarchy based primarily on birthright, where nobility held significant power and influence, and social mobility was limited.