With reference to India, Didwana, Kuchaman, Sargol and Khatu are the names of

1. A

   glaciers

   Glaciers. These are Rajasthan names, not Himalayan ice.

2. B

   mangrove areas

   Mangroves. Inland Thar, not coast.

3. C

   Ramsar sites

   Ramsar sites. Not this list as a class.

4. D

   saline lakes

   Saline lakes. Didwana, Kuchaman, Sargol, Khatu — playas of Rajasthan.

Summary. Official key is (d) saline lakes. Didwana, Kuchaman, Sargol and Khatu are salt lakes / playas of the Rajasthan desert, not glaciers, mangroves or a Ramsar set.