Identify an Accurate Statement About the Zone of Proximal Development

Identify an accurate statement about the zone of proximal development.

A) It is the distance between what a child can learn alone and what that child can learn assisted by someone else, usually an adult.
B) It is the zone in which a child engages with the least number of people for effective learning.
C) It is the zone where a learner completes a task unaided.
D) The phrase was coined by Jean Piaget.