Jean Piaget's theory of development states that:

(a) Children are egocentric during the stage of pre-operational thought
(b) Object permanence is developed during concrete operational stage
(c) Conservation and reversibility appear in formal operations
(d) Child development is largely culturally determined
✅ Correct option: (a)
Explanation: Egocentrism is a key feature of Piaget’s pre-operational stage.