The correct answer is option 'D' - Sunderbans.

The Sunderbans is included in the world list of biosphere reserves by UNESCO. Let's delve into the details of the Sunderbans and why it has received this prestigious recognition.

- The Sunderbans is a vast mangrove forest located in the delta of the Ganges, Brahmaputra, and Meghna rivers in the Bay of Bengal. It stretches across parts of India and Bangladesh, covering an area of approximately 10,000 square kilometers.

- The region is known for its unique ecosystem, characterized by extensive mangrove forests, diverse flora and fauna, and a complex network of tidal waterways. It is home to numerous endangered species, including the Royal Bengal Tiger, Indian python, Ganges River dolphin, and saltwater crocodile.

- In recognition of its ecological significance and biodiversity, the Sunderbans was designated a Biosphere Reserve by UNESCO in 2001. A biosphere reserve is an internationally recognized area that seeks to balance conservation, sustainable development, and research. It aims to promote the conservation of biodiversity, provide opportunities for scientific research and monitoring, and support sustainable development practices.

- The Sunderbans Biosphere Reserve is divided into three zones: the core zone, the buffer zone, and the transition zone. The core zone is the most strictly protected area and serves as a natural habitat for wildlife. The buffer zone surrounds the core area and allows for regulated human activities such as tourism, research, and traditional resource use. The transition zone includes the peripheral areas and focuses on sustainable development and community participation.

- The Sunderbans Biosphere Reserve is not only important for its ecological value but also for its socio-economic significance. It supports the livelihoods of thousands of people who depend on its resources for fishing, honey collection, and timber extraction. However, these activities need to be managed sustainably to ensure the long-term health of the ecosystem.

In conclusion, the Sunderbans, with its rich biodiversity and unique mangrove ecosystem, has been recognized by UNESCO as a Biosphere Reserve. This designation highlights the importance of protecting and conserving this remarkable natural heritage while promoting sustainable development in the region.