What is common to the places known as Aliyar, Isapur and Kangsabati?

1. A

   Recently discovered uranium deposits

   (a) Recently discovered uranium deposits. These names are not India’s uranium news sites (compare Tummalapalle, Jaduguda), so this is not the key.

2. B

   Tropical rain forests

   (b) Tropical rain forests. Aliyar is in Tamil Nadu’s Anamalais irrigation belt, Isapur in Maharashtra, Kangsabati in West Bengal — not a shared rainforest identity, so this is not the key.

3. C

   Underground cave systems

   (c) Underground cave systems. Not what these three share, so this is not the key.

4. D

   Water reservoirs

   (d) Water reservoirs. Aliyar (Tamil Nadu), Isapur (Maharashtra) and Kangsabati (West Bengal) are dam/reservoir projects. That common identity is the official key.

Summary. Official key is (d) water reservoirs. Three irrigation reservoirs in three States, not a uranium, rainforest or cave set. Honour the stored letter (d).