किसने विकास को परिभाषित करते हुए कहा था, 'विकास का अर्थ परिवर्तनों की एक प्रगतिशील श्रृंखला से है जो परिपक्वता और अनुभव के परिणामस्वरूप होती है'?

According to Piaget, the stage in which children develop object permanence is:

Kohlberg's highest stage of moral development is characterized by:

Which of the following behaviors in early childhood would MOST strongly indicate a need for developmental screening for Intellectual and Developmental Disabilities (IDD)?