How many of the following are ex situ approaches to conserving biodiv…

The correct answer is Option (3) → Four

In ex situ (off site) conservation, threatened plants and animals, or their gametes and seeds, are kept and cared for outside their natural habitat. In situ conservation protects them where they live, by protecting the whole ecosystem.

Cryopreservation of gametes of threatened species — Ex situ. Gametes are preserved in viable and fertile condition for long periods, away from the habitat.

Sacred groves — In situ. Tracts of forest are protected where they stand, with all their trees and wildlife.

Propagation of plants by tissue culture — Ex situ. Plants are multiplied in the laboratory.

Seed banks — Ex situ. Seeds of different genetic strains of commercially important plants are stored for long periods.

Biosphere reserves — In situ. Biodiversity-rich regions are legally protected along with their ecosystems.

Wildlife safari parks — Ex situ. Like zoological parks, they keep threatened animals in a special setting.

So four of the six are ex situ approaches.

NCERT Extract:
How do we Conserve Biodiversity? – “… Ex situ Conservation– In this approach, threatened animals and plants are taken out from their natural habitat and placed in special setting where they can be protected and given special care. Zoological parks, botanical gardens and wildlife safari parks serve this purpose. … Now gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques, eggs can be fertilised in vitro, and plants can be propagated using tissue culture methods. Seeds of different genetic strains of commercially important plants can be kept for long periods in seed banks.”
How do we Conserve Biodiversity? – “… In India, ecologically unique and biodiversity-rich regions are legally protected as biosphere reserves, national parks and sanctuaries.”