​There is a species that is critically endangered, found in the Russian Far East. It is solitary, but it has been reported that some males stay with females after mating, and may even help with rearing the young. Identify this species.​

Correct option is A

Explanation-

Option a - Amur Leopard (Panthera pardus orientalis)
Critically Endangered (IUCN Red List)
They are found primarily in the Russian Far East (Amur-Heilong region), with some in northeastern China.
Population estimated at ~100 individuals in the wild, making it one of the rarest big cats.
They are solitary by nature, but some males have been observed staying with females after mating. Occasionally, they assist in protecting or rearing cubs — a rare trait among big cats.

Incorrect option -
Option b - Snow Leopard
They are native to Himalayas and Central Asia, not Russian Far East. They are also  solitary, but no known behavior of males helping rear cubs.
Option c - Arctic Fox
They are native to Arctic regions, not in the Russian Far East forests. They are also not critically endangered.
Option d - Black-footed Ferret
They are native to North America, especially U.S. grasslands. They are critically endangered but not found in Russia and doesn't match the big cat description.

So, the correct answer is option a - Amur leopard.