Which of the Following Was a Finding of Kail's (1990,2008)research

Which of the following was a finding of Kail's (1990,2008) research on children's cognitive development?

A) That younger children's short-term memories are more limited than those of older children
B) That Piaget greatly underestimated the abilities of younger children
C) That older children's long-term memories are more accurate than those of younger children
D) That Vygotsky's concept of the zone of proximal development was only applicable to the memory of younger children