The Zone of Proximal Development Concerns the Gap Between What

The zone of proximal development concerns the gap between what children can:

A) Act out with or without inanimate toys
B) Understand in the formal operations stage and what they can understand in the concrete operations stage
C) Say versus what they can comprehend on their own
D) Manipulate in their mind and what they can manipulate physically
E) Achieve on their own and what they can achieve with others' help