Explanation:

Work on India’s first dolphin research centre was set to start in Patna post-monsoon. The National Dolphin Research Centre would boost conservation efforts for river dolphins and would provide an opportunity for in-depth research on them.   The NDRC is coming up on the 4,400 square metre plot of land on the premises of Patna University, near the banks of the Ganga.  Bihar is home to around half of the estimated 3,000 Gangetic dolphins in India.  About Gangetic Dolphin

• The Gangetic river dolphin is India’s national aquatic animal.  
• It is a Schedule I animal under the Wild Life (Protection) Act, 1972.  
• It has been declared an endangered species by the International Union for Conservation of Nature (IUCN). 
• The Gangetic river dolphin is one of four freshwater dolphin species in the world.  
• The other three are found in the Yangtze river in China (now extinct), the Indus river in Pakistan and the Amazon river in South America. 
• The dolphin is found in India, Bangladesh and Nepal. It is blind and finds its way and prey in river waters through echolocation.  
• Dolphins prefer water that is at least five to eight feet deep. They are usually found in turbulent waters, where there are enough fish for them to feed on. 
• Gangetic dolphins live in a zone where there is little or no current, helping them save energy. If they sense danger, they can dive into deep waters. The dolphins swim from the no-current zone to the edges to hunt for fish and return. 

Hence option 4th is correct.