The correct option is Seshachalam.
Explanation
Biosphere Reserves (BRs) are large areas of bio-cultural landscapes designated for the conservation of biodiversity and sustainable development. While the Government of India designates Biosphere Reserves within the country, the UNESCO Man and the Biosphere (MAB) Programme recognizes a subset of these under the World Network of Biosphere Reserves (WNBR) based on international criteria.- Nilgiri Nilgiri: Incorrect. The Nilgiri Biosphere Reserve, located at the tri-junction of Tamil Nadu, Kerala, and Karnataka, was the first Biosphere Reserve in India to be included in the UNESCO World Network (designated in 2000).
- Sunderban Sunderban: Incorrect. Located in the delta of the Ganges and Brahmaputra in West Bengal, Sunderban was included in the UNESCO World Network in 2001. It is globally renowned for its mangrove forests and the Royal Bengal Tiger.
- Gulf of Mannar Gulf of Mannar: Incorrect. Situated in Tamil Nadu, the Gulf of Mannar Biosphere Reserve was included in the UNESCO World Network in 2001. It is the first marine Biosphere Reserve in India.
- Seshachalam Seshachalam: Correct. The Seshachalam Hills, located in the Eastern Ghats of Andhra Pradesh, were designated as a Biosphere Reserve by the Government of India in 2010. However, it has not been included in the UNESCO World Network of Biosphere Reserves to date.
Key Takeaway:
As of recent updates, India has 18 notified Biosphere Reserves. Out of these, 12 are recognized under the UNESCO World Network of Biosphere Reserves (WNBR). Seshachalam is a domestic Biosphere Reserve but is not part of the UNESCO network.