Explanation:

• Irrawaddy dolphins are naturally found in coastal areas in South and Southeast Asia, and in three rivers: the Ayeyarwady (Myanmar), the Mahakam (Indonesian Borneo) and the Mekong.
• In India, Irawaddy dolphins are mostly found in Chilika Lake of Odisha.

Platanista gangetica  or  Gangetic dolphin:

• It has been declared endangered by International Union for Conservation of Nature (IUCN).
• It has rudimentary eyes. From preying to surfing, dolphins do it through ultrasonic sound.
• It is India’s national aquatic animal and is popularly known as ‘Susu’
• They are distributed across seven states in India: Assam, Uttar Pradesh, Madhya Pradesh, Rajasthan, Bihar, Jharkhand and West Bengal.

Hence option 1st is correct.