* Critical Tiger Habitats (CTH), also known as core areas of tiger reserves, are identified under the Wild Life Protection Act, 1972 based on scientific evidence that such areas are required to be kept as inviolate for the purpose of tiger conservation. * Among the options given, Nagarjunsagar-Srisailam Tiger Reserve has the largest area under 'Critical Tiger Habitat'. It spreads over five districts and the total area of the tiger reserve is 3,728 sq. km.