Concept:According to Piaget, the concrete operational stage is the third stage of cognitive development. Its key achievement is the ability to conserve — understanding that quantity remains the same despite changes in appearance.
Explanation:Piaget’s four stages occur in a fixed order: sensorimotor (0–2 years), preoperational (2–7), concrete operational (7–12), and formal operational (12+).
In the concrete operational stage, children develop conservation of number, mass, weight, area, and volume.
For example, a child can conserve mass at age 7 and weight at age 9.
They also develop reversibility, seriation, and transitivity.
This stage is sometimes called the “gang age” due to increasing peer interaction and class inclusion.
Among the given options, only “ability to conserve” belongs to this stage.
- Hypothetico-deductive reasoning belongs to the formal operational stage.
- Secondary circular reactions belong to the sensorimotor stage.
- Animistic thinking belongs to the preoperational stage.
Thus, the major accomplishment of the concrete operational stage is the ability to conserve.
Answer:A. Ability to conserve