When Interpreting the Results of Studies Which Examine the Child

When interpreting the results of studies which examine the child outcomes associated with different parenting styles;one important limitation to keep in mind is that:

A) early developmental psychologists consistently underestimated the cognitive and social abilities of young children.
B) because this work is correlational,we can't specifically tell which factor causes the other.
C) this research fails to take the critical developmental variable of attachment into consideration.
D) because of their lack of cognitive development,it is difficult to accurately assess the behaviour of young children.