Which of the following statements is correct about Jean Piaget's theory of cognitive development? [CTET-Sept.-2016-II]

• A. The sequence of the stages can vary according to the cultural context of children.
• B. Piaget argues that instead of progressing through stages, cognitive development is continuous.
• C. Piaget has proposed five distinct stages of cognitive development.
• D. The stages are invariant which means that no stage can be skipped.17. The concept of 'conservation' as proposed by Jean Piaget means that