The correct answer is option 'B', West Bengal.

**Location of Sunderban:**

The Sunderban is located in the state of West Bengal, India. It is situated in the southern part of the state, near the Bay of Bengal. It is a vast mangrove forest and delta region that stretches across both India and Bangladesh.

**Sunderban National Park:**

The Sunderban is home to the Sunderban National Park, which is a UNESCO World Heritage Site. The national park covers an area of approximately 1,330 square kilometers, out of which about 426 square kilometers are located within the Indian territory.

**Importance of Sunderban:**

1. Mangrove Ecosystem: The Sunderban is known for its unique mangrove ecosystem. The region is characterized by a network of tidal waterways, mudflats, and small islands covered with dense mangrove forests. This ecosystem provides a habitat for a wide variety of plant and animal species, including the Royal Bengal Tiger, estuarine crocodile, and numerous bird species.

2. Biodiversity: The Sunderban is rich in biodiversity. It is home to many endangered species, including the Royal Bengal Tiger, which is the main attraction of the national park. The Sunderban is also known for its diverse avian population, with over 250 species of birds recorded in the area.

3. Conservation Efforts: The Sunderban has been the focus of conservation efforts to protect its unique ecosystem and wildlife. The national park is managed by the West Bengal Forest Department, which works towards preserving the flora and fauna of the region. Various measures have been taken to ensure the conservation of the Royal Bengal Tiger, including anti-poaching patrols and habitat restoration projects.

4. Ecotourism: The Sunderban attracts a large number of tourists every year who come to experience its natural beauty and wildlife. Ecotourism has been promoted in the region to provide sustainable livelihoods to the local communities and raise awareness about the importance of conservation.

In conclusion, the Sunderban is located in West Bengal, India. It is a unique mangrove forest and delta region that is home to a diverse range of flora and fauna, including the Royal Bengal Tiger. The region's significance lies in its rich biodiversity, conservation efforts, and promotion of ecotourism.

Sunder ban is in West Bengal as sunder ban is formed in Ganga Brahmaputra basin which is in West Bengal