The correct answer is: A. Bhagalpur
The Bihar Dolphin Sanctuary is a protected area for the Ganges river dolphin in Bhagalpur district, Bihar, India. It was established in 1991 and covers an area of 1,200 square kilometers. The sanctuary is home to a population of about 1,000 dolphins.
The Ganges river dolphin is a freshwater dolphin that is found in the Ganges River and its tributaries in India, Nepal, and Bangladesh. It is the only freshwater dolphin species in Asia. The Ganges river dolphin is a threatened species and is listed as Endangered on the IUCN Red List.
The main threats to the Ganges river dolphin are habitat loss, pollution, and overfishing. Habitat loss is caused by the construction of dams and barrages on the Ganges River. Pollution is caused by the discharge of industrial and agricultural waste into the river. Overfishing is caused by the use of nets that are too small to allow the dolphins to escape.
The Bihar Dolphin Sanctuary is an important conservation effort to protect the Ganges river dolphin. The sanctuary provides a safe haven for the dolphins and helps to reduce the threats to their survival.
Option A: Bhagalpur is the correct answer. The Bihar Dolphin Sanctuary is located in Bhagalpur district, Bihar, India.
Option B: Patna is the capital of Bihar. It is not home to the Bihar Dolphin Sanctuary.
Option C: Buxar is a city in Bihar. It is not home to the Bihar Dolphin Sanctuary.
Option D: Madhubani is a district in Bihar. It is not home to the Bihar Dolphin Sanctuary.