The first Biosphere Reserve of India is located in the Nilgiri region, hence the correct answer is option 'A'.

The Nilgiri Biosphere Reserve is a significant ecological hotspot located in the Western Ghats of India. It was established in 1986 and was the first biosphere reserve in the country. Let's explore more about this fascinating region.

The Nilgiri Biosphere Reserve covers an extensive area of approximately 5,520 square kilometers. It spans across three states - Tamil Nadu, Kerala, and Karnataka. The region is known for its rich biodiversity and unique ecosystems.

Here are some key features of the Nilgiri Biosphere Reserve:

1. Location: The Nilgiri Biosphere Reserve is situated in the Western Ghats, a mountain range along the western coast of India. It is located at the tri-junction of Tamil Nadu, Kerala, and Karnataka.

2. Biodiversity: The reserve is home to a diverse range of flora and fauna. It houses several endangered species like the Nilgiri tahr, Bengal tiger, Asian elephant, Indian leopard, lion-tailed macaque, and many more. The region also has numerous endemic plant species.

3. Core and Buffer Zones: The Nilgiri Biosphere Reserve is divided into core and buffer zones. The core zone comprises protected areas like national parks and wildlife sanctuaries, while the buffer zone consists of areas where sustainable development activities are allowed.

4. Cultural Significance: The region has a rich cultural heritage with indigenous tribal communities like the Toda, Kota, and Kurumba residing here. These communities have a deep connection with the land and have been practicing traditional sustainable practices for centuries.

5. Conservation Efforts: The Nilgiri Biosphere Reserve plays a crucial role in conserving the unique ecosystems of the Western Ghats. It focuses on biodiversity conservation, research, education, and sustainable development. Various measures are taken to protect the flora, fauna, and natural habitats within the reserve.

In conclusion, the first Biosphere Reserve of India, the Nilgiri Biosphere Reserve, is located in the Nilgiri region of the Western Ghats. It is a prime example of the country's efforts towards biodiversity conservation and sustainable development.