The underlined word "precept" (Para. 3) probably means ______ .

A．observe the roles themselves
B．be aware of the marked difference between adults and children
C．forbid things which have no foundation in morality
D．satisfy their children's needs

A．parents should be strict with their children
B．parental controls satisfy only the needs of the parents and the values of the community
C．parental restrictions vary, and are not always enforced for the benefit of the children alone
D．parents vary in their strictness towards their children according to the situation