a) Glaciers

 b) Mangrove areas 

c) Ramsar sites 

d) Saline lakes 

Ans: d

Explanation: 

The Rajasthan Plain

Thar or the Great Indian Desert, covers western Rajasthan and the adjoining parts of Pakistan.

The eastern edge of the Thar Desert there are several saline lakes. They are a great source of common salt and many other salts. The Sambhar, the Didwana, the Degana, the Kuchaman, the Sargol and the Khatu are some of the important lakes. The largest and most outstanding is the Sambhar Lake.

Hence, option d is correct.

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