Answer:
Captive breeding
Step-by-step explanation:
Endangered species, such as the Black Rhino, Saola, Cross River Gorrillas, the Blue Whale, and a host of others, are species that are critically under the verge of extinction either as a result of the destruction of their habitat or poaching/overhunting, which has really led to steep decline in their population.
Several attempts have been made and ate being made to ensure the preserve and protect these endangered species form going extinct.
However, the best of such measures or practices is arguably referred to as Captive Breeding.
Captive breeding involves the capturing of some of these endangered species and transporting them to enclosed and monitored facilities such as zoos in other to promote the increase preservation and survival of these species and ensuring they don't go extinct.
In most cases, when a considerable increase in population in these facilities is established through breeding, some of them are later on reintroduced to their natural habitat in the wild. This do not only ensure biodiversity, it also ensures the population of the endangered species to grow and avoid such species from going extinct.