A unique high-altitude mammal found in Arunachal Pradesh is the:

Mishmi Takin
Nilgiri Tahr
Markhor
Himalayan Brown Bear

The correct answer is (a) Mishmi Takin.

The Mishmi Takin is a unique high-altitude mammal found in Arunachal Pradesh. It is a large, heavy animal with a long, shaggy coat. It has a large head with a pair of long, curved horns. The Mishmi Takin is a herbivore and its diet consists of grasses, leaves, and shoots. It is a social animal and lives in herds of up to 50 individuals. The Mishmi Takin is an endangered species and its population is declining due to habitat loss and hunting.

The Nilgiri Tahr is a wild goat found in the Western Ghats of India. It is a large, agile animal with a long, shaggy coat. It has a pair of long, curved horns. The Nilgiri Tahr is a herbivore and its diet consists of grasses, leaves, and shoots. It is a social animal and lives in herds of up to 50 individuals. The Nilgiri Tahr is a vulnerable species and its population is declining due to habitat loss and hunting.

The Markhor is a wild goat found in the mountains of Central Asia. It is a large, powerful animal with a long, shaggy coat. It has a pair of long, spiral horns. The Markhor is a herbivore and its diet consists of grasses, leaves, and shoots. It is a social animal and lives in herds of up to 50 individuals. The Markhor is a vulnerable species and its population is declining due to habitat loss and hunting.

The Himalayan Brown Bear is a bear found in the mountains of Central Asia. It is a large, powerful animal with a long, shaggy coat. It has a pair of short, curved horns. The Himalayan Brown Bear is an omnivore and its diet consists of grasses, leaves, shoots, fruit, insects, small mammals, and carrion. It is a solitary animal and lives in a home range of up to 100 square kilometers. The Himalayan Brown Bear is a vulnerable species and its population is declining due to habitat loss and hunting.