Biosphere reserve is the protected land or area that conserve all life forms.
Biosphere reserve is divided into 3 zones - core, buffer and manipulation.Core zone - Human activities are prohibited in this zone.
Buffer zone - Limited human activity is allowed in the buffer zone.
Manipulation or Transition zone - Several human activities are allowed in the manipulation zone e.g., settlements, cropping, forestry, recreation etc.
Hence, the correct answer is option D.