The correct option is C In situ conservation
A biosphere reserve is an ecosystem with plants and animals of unusual scientific and natural interest. It is a title given by UNESCO to help protect the sites. The plan is to promote management, research and education in ecosystem conservation. This includes the 'sustainable use of natural resources'.
In situ conservation is on-site conservation or the conservation of genetic resources in natural populations of plant or animal species, such as forest genetic resources in natural populations of tree species.