The "problem of the match", as discussed by J. McVicker Hunt, is

A. Setting up on environment that’s familiar yet appropriately challenging

B. Matching children with like interests into care groups

C. The difficulty of matching voice with behavioral actions

D. Matching caregiver background and experience with age group

J. McVicker Hunt proposed a concept known as "problem of the match" that illustrates the importance of the development of the mental functions in children. In this concept, a child forms higher abilities through learning activities that are not too simple but not too challenging. Therefore, the child is able to perform a task with only a little help.

In the problem of the match, the adult analyses and is able to adjust the level of challenge of the previously-mentioned task in order to ensure that the child is learning and, at the same time, avoiding frustration by being too challening or overwhelming.

Therefore, this concept refers to setting up an environment that's familiar yet appropriately challening.