What Would Sociologists Conclude Is One Difficulty That Arises When

What would sociologists conclude is one difficulty that arises when applying Jean Piaget's approach to the study of child development to all children across all societies and cultures?

A) In American culture, the family is far more important than any other agent of socialization.
B) Schooling is far more important than the family in the concrete operational stage.
C) Piaget underestimated the role of the ego in children.
D) The stages of cognitive development may not always follow a smooth and progressive path.