The correct answer is (d), Odisha.
In February 2015, the Odisha government launched a “dolphin-census” in the coastal eco-system and shorelines of the State. The census was conducted by the State Forest Department in collaboration with the Wildlife Institute of India (WII). The objective of the census was to assess the population of dolphins in Odisha and to identify the threats to their survival.
The census was conducted using a combination of methods, including boat surveys, aerial surveys, and interviews with fishermen. The results of the census showed that there are approximately 1,000 dolphins in Odisha. The most common species of dolphin found in Odisha is the Irrawaddy dolphin.
The census also identified a number of threats to the survival of dolphins in Odisha, including habitat loss, pollution, and entanglement in fishing nets. The Odisha government has taken a number of measures to protect dolphins, including the creation of dolphin sanctuaries and the enforcement of fishing regulations.
Gujarat, Karnataka, and West Bengal are also coastal states with dolphins. However, there is no evidence that these states have conducted a dolphin-census in recent years.