The correct option is A Ex-situ conservation
Ex-situ conservation means conservation outside the habitats by perpetuating sample population in genetic resource centers. For example, botanical gardens.
Off-site conservation is another name for Ex-situ conservation.
In-situ conservation is the conservation of living resources through their maintenance within the natural ecosystems in which they occur. For example, national parks.
Cryopreservation is the technique of germplasm preservation in liquid nitrogen at -196° C.
Gingko Biloba has been conserved by Ex-situ conservation, hence it is no longer an endangered species. So, the correct answer is 'Ex-situ conservation'.