Jean Piaget made a systematic study of cognitive development among children of different age groups and he categorized it into different developmental stages. These stages are-Sensory-motor stage (0 to 2 years)Pre-operational stage (2 to 6 years)Concrete operational stage (6 to 11 years)Formal Operational stage (11+ years to adolescence).?Collective Monologue: A form of egocentric, unsocialized speech in which children talk among themselves without apparently communicating with each other in a meaningful way.This concept of the collective monologue is given by Jean Piaget in his Pre- Operational stage.So Option (1) is the correct answer.Important PointsSensory Motor”Goal actionThe hallmarks of achievement at this stage are smoother and more coordinated reflex activities, prominent self-investigative behavior, reaching out reactions, and the emergence of more goal-directed behavior.Pre-Operational”Collective MonologueWhen the children use a unique form of speech, children in groups talk but do not really interact.Concrete Operational “ ReversibilityIt is the ability by which the child becomes capable of following a series of actions and then being able to follow back or in other words reverse these series of actions mentally.Formal Operational “ Adolescent ego-centrismAdolescent egocentrism includes a belief system carried by adolescents that makes them consider themselves special and unique. Adolescent egocentrism is also characterized by an imaginary audience with an increased self-consciousness.Additional InformationTheoriesProposed bySocio-cultural theoryLev VygotskyTheory of cognitive LearningJerome BrunerSocial learning theoryAlbert Bandura