Answer:
socialization
Explanation:
Socialization refers to a mechanism that presents the social norms and customs to people belonging the society. It helps the members of a society to adapt to it effectively and therefore helps to stabilize society. Social institutions like family, friends, teachers, religious leaders, etc all play significant roles within the process of socialization of an individual. A per the question, older sisters guides her younger system about the social environment of school and therefore helps in her socialization process.
