During the sensorimotor stage, which major development do children achieve?

• A. Conservation
• B. Abstract Reasoning
• C. Egocentrism
• D. Object Permanence

Answer: (D)

Object permanence—the understanding that objects continue to exist even when they are not seen or heard—is the major development achieved during the sensorimotor stage. This stage, roughly from birth to about two years, moves children from reflexive actions to more intentional interactions with the world, and, in the later months, they begin to search for partially hidden objects, showing they remember they still exist even when out of sight. Concepts like conservation (not yet present until the concrete operational stage), abstract reasoning (formal operational stage), and egocentrism (prevalent in the preoperational stage) come later in development, not during the sensorimotor period.