It's a general belief that a child' s later character and personality is _________ decided by his early experiences both at home and in school.

A．to define the term social class does not involve much difficulty
B．there is much alternation in people's social classes
C．to evaluate a person' s social class is a very complex procedure
D．we can tell which social class a person belongs to by the way he behaves

A．The Criteria for Classifying Social Groups
B．Social Classes
C．Changes in Social System
D．The Evolution of Human Society