Explanation:

Only statements 1&3 are correct.

• Bihar’s only wetland of international importance Kanwar Lake under the Ramsar Convention lies neglected and is on the brink of drying up.

• It is Asia’s largest freshwater oxbow lake and Bihar’s only Ramsar site.

• It is also known as Kabartal jheel.

• It is a residual oxbow lake, formed due to the meandering of Gandak river, a tributary of Ganga. 

• It is covering the majority of the Indo-Gangetic plains in northern Bihar,

• The wetland is an important stopover along the Central Asian Flyway, with 58 migratory waterbirds using it to rest and refuel.

• It is also a valuable site for fish biodiversity with over 50 species documented.

• Five critically endangered species inhabit the site, including three vultures – the red-headed vulture (Sarcogyps calvus), white-rumped vulture (Gyps bengalensis) and Indian vulture (Gyps indicus) – and two waterbirds, the sociable lapwing (Vanellus gregarius) and Baer’s pochard (Aythya baeri).

• Threats: Major threats to the site include water management activities such as drainage, water abstraction, damming and canalization.

Hence option 2nd is correct.