To solve this problem, we need to identify which option is related to ex-situ conservation of threatened animals and plants.$\newline$Ex-situ conservation involves the preservation of components of biological diversity outside their natural habitats.$\newline$Let's analyze each option:$\newline \bullet$Option 1: Biodiversity hot spots.$\newline$ - Biodiversity hot spots are regions with a high level of species richness and endemism.$\newline$ - They are areas of in-situ conservation, where conservation efforts are focused on protecting species in their natural habitats.$\newline \bullet$Option 2: Amazon rainforest.$\newline$ - The Amazon rainforest is a vast tropical rainforest known for its biodiversity.$\newline$ - It is an example of in-situ conservation, as it involves protecting species within their natural environment.$\newline \bullet$Option 3: Himalayan region.$\newline$ - The Himalayan region is known for its diverse ecosystems and species.$\newline$ - Conservation efforts here are also in-situ, focusing on preserving species in their natural habitats.$\newline \bullet$Option 4: Wildlife Safari parks.$\newline$ - Wildlife Safari parks are facilities where animals are kept in large enclosures and are protected outside their natural habitats.$\newline$ - This is an example of ex-situ conservation, as it involves the conservation of species outside their natural environments.$\newline$Therefore, the correct option related to ex-situ conservation is Option 4: Wildlife Safari parks.$\newline$This corresponds to the correct option, which is Option 4.