Final answer:
The correct answer is option d. A major criticism of Jean Piaget's cognitive development theory is that he often underestimated the cognitive abilities of children, with later research indicating that children reach cognitive milestones earlier than he suggested.
Step-by-step explanation:
The question concerns a major criticism of Jean Piaget's cognitive development theory. Piaget suggested that children progress through distinct stages of cognitive development: sensorimotor, preoperational, concrete operational, and formal operational.
One significant criticism of his theory, as evidenced by subsequent research, is that he often underestimated the cognitive abilities of children. Studies by researchers such as Baillargeon indicated that children achieved cognitive milestones earlier than Piaget had described, showing that even very young infants have an understanding of the world that Piaget believed was beyond their abilities at that stage.