Which one of the following is not a method of in-situ conservation of…

The correct answer is Option (4) → Botanical garden

In situ (on site) conservation protects species in their natural habitat, along with the whole ecosystem. Ex situ (off site) conservation takes threatened species out of their habitat into special places.

Option (1) Sacred grove — An in situ method.

Option (2) Biosphere reserve — An in situ method.

Option (3) Wildlife sanctuary — An in situ method.

Option (4) Botanical garden — Not an in situ method. Plants are grown away from their natural habitat; it is ex situ conservation, like zoos and seed banks.

NCERT Extract:
Summary – “Biodiversity conservation may be in situ as well as ex situ. In in situ conservation, the endangered species are protected in their natural habitat so that the entire ecosystem is protected. … Our country’s in situ conservation efforts are reflected in its 14 biosphere reserves, 90 national parks, > 450 wildlife sanctuaries and many sacred groves. Ex situ conservation methods include protective maintenance of threatened species in zoological parks and botanical gardens, in vitro fertilisation, tissue culture propagation and cryopreservation of gametes.”