Final answer:
Early psychologists, including Watson, believed that parents and the child's environment played a decisive role in development. Family is also considered the most influential factor in a child's political socialization.
Step-by-step explanation:
Early psychologists like Watson viewed environment as "all powerful" concerning the development of a child. The correct choice from the given options would be parents as they are considered an integral part of the child's environment. Watson and other behaviorists believed that environmental influences, particularly the parenting practices, had a significant impact on shaping a child's personality and behavior.
The most important influence on political socialization is traditionally considered to be the family. As the earliest agent of socialization, family members, societal norms, and cultural background all contribute to instill values and beliefs in a child. While religion, peers, and mass media also play significant roles, the family is often seen as the primary and most influential force in the political socialization process.