Photo credit: Hair Artist Sharlena Bell
Positions 1, 2, and 3 - are clearly haircut status in the picture above
Position 4 is called a dusting off of the ends.
The longer the hair; the less important the question of where to cut becomes.
Position 1 - would give maximum thickness, movement, and restore hair to a healthy reset.
Ultimately, I would cut between Positions 3 and 4 unless the client is certain that she wants a "chunky" liberal cut.