Vygotsky's Theory About the ZPD Means That

Vygotsky's theory about the ZPD means that

A) adults should show infants how to do something new.
B) adults should let babies repeat the same activities until they are well established.
C) adults should see if babies are meeting developmental guidelines.
D) adults should help babies in whatever ways they need to succeed in a new, slightly harder, task than they have tried before.