To whom is the theory of "Looking-glass-self" attributed

The marriage of a women to a man of lower social status, rank or age is called as

A rule of marriage which restricts the selection of mates within one's own caste group is termed as

It is one of the characteristic features of Hindu Joint family system

Trade union is an example for 

Identify the social group in which the social relations between its members are impersonal, contractual and economic in nature