A flagship species found in Nagaland, also the state bird, is the:

Blyth's Tragopan
White-winged Wood Duck
Hoolock Gibbon
Golden Langur

The correct answer is: a) Blyth’s Tragopan.

Blyth’s Tragopan is a species of bird in the family Phasianidae. It is found in the eastern Himalayas, from Bhutan and northeastern India to Myanmar and Yunnan. It is a shy and elusive bird, and its natural habitat is subtropical or tropical moist montane forests. It is threatened by habitat loss and hunting.

The White-winged Wood Duck is a species of duck in the family Anatidae. It is found in the eastern Himalayas, from Bhutan and northeastern India to Myanmar and Yunnan. It is a resident bird of evergreen forests, and is not migratory. It is a small duck, with a length of 38–45 cm. The male is black with a white wing patch, while the female is brown.

The Hoolock Gibbon is a species of gibbon in the family Hylobatidae. It is found in the eastern Himalayas, from Bhutan and northeastern India to Myanmar and Yunnan. It is a black gibbon with a white face and throat. It is a social animal, living in groups of up to 12 individuals.

The Golden Langur is a species of langur in the family Cercopithecidae. It is found in the eastern Himalayas, from Bhutan and northeastern India to Myanmar and Yunnan. It is a golden-colored langur with a black face and throat. It is a social animal, living in groups of up to 20 individuals.

Blyth’s Tragopan is the state bird of Nagaland. It is a shy and elusive bird, and its natural habitat is subtropical or tropical moist montane forests. It is threatened by habitat loss and hunting.