Which Child Does Piaget's Theory Have the Most Difficulty Explaining

Multiple Choice

Which child does Piaget's theory have the most difficulty explaining?

A) Ivy, who has mastered the conservation and three-mountain tasks
B) Rose, who fails both the conservation and three-mountain tasks
C) Daisy, who has mastered the conservation task but fails the three-mountain task
D) Mbali, who not only has mastered the conservation and three-mountain tasks but can explain the intricacies of these tasks to others