Answer:

The correct answer is option 'D', Gulf of Kutch.

Explanation:
Biosphere reserves are areas that are recognized internationally for their unique ecosystems, biodiversity, and cultural heritage. They are designated and managed under the Man and the Biosphere (MAB) Program of UNESCO. Biosphere reserves aim to conserve the natural resources and biodiversity within their boundaries while also promoting sustainable development.

Great Nicobar:
Great Nicobar is the largest island in the Nicobar group of islands, which is located in the eastern Indian Ocean. It is home to diverse ecosystems, including rainforests, wetlands, and mangroves. Great Nicobar Biosphere Reserve was established in 1989 and covers an area of approximately 885 square kilometers. It is recognized for its rich biodiversity, including several endemic species of flora and fauna.

Sunderbans:
Sunderbans is a vast mangrove forest located in the Ganges Delta, spanning parts of India and Bangladesh. It is the largest mangrove ecosystem in the world and is home to the Royal Bengal Tiger, as well as other endangered species. Sunderbans Biosphere Reserve was established in 1989 and covers an area of approximately 9,630 square kilometers. It is recognized for its unique tidal mangrove forests and its importance in maintaining the ecological balance of the region.

Nanda Devi:
Nanda Devi Biosphere Reserve is located in the state of Uttarakhand in northern India. It encompasses the Nanda Devi National Park and the Valley of Flowers National Park. Nanda Devi is the highest peak in India outside the Himalayas and is surrounded by a diverse range of ecosystems, including alpine meadows, glaciers, and high-altitude forests. The biosphere reserve was established in 2004 and covers an area of approximately 2,236 square kilometers. It is recognized for its ecological significance and as a habitat for several endangered plant and animal species.

Gulf of Kutch:
Gulf of Kutch is a large inlet of the Arabian Sea located in the state of Gujarat, western India. While the Gulf of Kutch is an important coastal ecosystem, it has not been designated as a biosphere reserve so far. However, it is worth noting that the Gulf of Kutch is home to several marine protected areas, including the Marine National Park in the Gulf of Kutch, which was established in 1982. These protected areas aim to conserve the diverse marine life and coastal ecosystems found in the region.