2. the zone of proximal development is a) the period in a child’s life where they develop most noticeably b) how long it takes for one to master a stage before moving on to the next stage c) the level of functioning of one who has already mastered a particular stage d) the distance between a person’s current developmental level and their potential development level with assistance from a more capable ally

D) The distance between a person’s current developmental level and their potential development level with assistance from a more capable ally

Explanation:

This concept was given by a Soviet psychologist named Lev  Vygotsky. A child always followed elders in family and develop the ability to do a task without any help. It is the distance between actual development indicated by independent problem solving and potential development under the guidance of capable peers. Now it has been modified, expanded and changed in new concepts. Scaffolding is another concept that is closely related to ZPD concepts. Thus proximal is referred to as those skills which are close to the learner and can mastery over them.