Which of the Following Statements Regarding Jean Piaget's Theory of Cognitive

Which of the following statements regarding Jean Piaget's theory of cognitive development is most accurate?

A) Research results suggest that Piaget's theory was relatively accurate for the earlier stages but research has not been as supportive of the formal operational stage.
B) Research results are largely consistent with Piaget's theory, but there are some important limitations and inaccuracies.
C) Research regarding the validity of Piaget's theory has yet to be conducted.
D) Research results suggest that Piaget's model is relatively accurate and, though the speed of cognitive development may be influenced by cultural factors, children cross culturally still pass through all the stages and in the correct order.