Two Children Are in the Same Stage of Cognitive Development

Multiple Choice

Two children are in the same stage of cognitive development and both can't solve problems involving conservation of number. However, when one of the children is given assistance, she is able to correctly solve such problems. When the other child receives the same help, he is still unable to solve them. This example best demonstrates

A) how cognitive and moral reasoning can interact with one another
B) how early problems with object permanence can influence later development
C) the importance of egocentrism with regard to problem solving
D) the concept of a proximal zone of development