The research that examined the attitudes of women who were pregnant and then 4 months after they gave birth is an example of __________ research.

The research that examined the attitudes of women who were pregnant and then 4 months after they gave birth is an example of __________ research. 

 longitudinal

 cross-sequential

 cross-sectional

 case study

Baby Hugh enjoys playing with his dad's keys, but when his dad takes them away, Hugh does not search for them. Piaget would say that is because Hugh does not understand:

A.egocentrism.

B.conservation.

C.object permanence.

D.affordances.