Which of these is related to Ex-situ conservation of threatened plants and animals?

The correct option is Wildlife safari parks.

To understand why this is correct, let us break down the concepts of biodiversity conservation. Biodiversity conservation is broadly categorized into two types: In-situ (on-site) conservation and Ex-situ (off-site) conservation.

1. In-situ Conservation (On-site):
This method involves protecting and conserving threatened species within their natural habitats and ecosystems. Examples include national parks, biosphere reserves, wildlife sanctuaries, biodiversity hotspots, and natural forests like the Amazon rainforest or regions like the Himalayas.

2. Ex-situ Conservation (Off-site):
This method involves conserving threatened plant and animal species outside their natural habitats in human-controlled environments. It is particularly useful for species that are critically endangered or facing an immediate threat of extinction in the wild. Examples include botanical gardens, zoological parks, gene banks, seed banks, and wildlife safari parks.

Let us evaluate the given options:
- Biodiversity hotspots: These are natural areas with high levels of species richness and endemism, representing in-situ conservation.
- Wildlife safari parks: These are human-managed, protected areas where animals are kept in captivity or semi-natural enclosures outside their original wild habitats. Hence, it is an ex-situ conservation method.
- Amazon rainforest: This is a massive natural ecosystem, representing in-situ conservation.
- Himalayan region: This is a natural geographical region and a biodiversity hotspot, representing in-situ conservation.

Therefore, Wildlife safari parks is the only option that represents ex-situ conservation.