A) Core zone includes the protected areas, and are represented by the biosphere reserves.
B) Buffer zone includes the area which surrounds the core area. The activities which are allowed, they help to protect it.
C) Manipulation zone is the outermost area of the biosphere reserve. Several human activities like settlements, cropping, recreation, and forestry are carried out in such areas without disturbing the environment.
So, the correct answer is 'Manipulation zone'.