The term 'IndARC', sometimes in the news, is the name of

1. A

   an indigenously developed radar system inducted into Indian Defence

   IndARC is not a defence radar. Indigenous radar programmes use other names. This option is not the key.

2. B

   India's satellite to provide services to the countries of Indian Ocean Rim

   It is not an Indian Ocean Rim communication satellite. This option is therefore wrong.

3. C

   a scientific establishment set up by India in Antarctic region

   India’s Antarctic stations are Maitri and Bharati (and earlier Dakshin Gangotri). IndARC is not an Antarctic base. This option is not the key.

4. D

   India's underwater observatory to scientifically study the Arctic region

   IndARC is India’s first underwater moored observatory in the Arctic, deployed in Kongsfjorden, Svalbard, for polar ocean and climate studies. This option is the official key.

Summary. Official key is (d) India’s underwater observatory to scientifically study the Arctic region. IndARC was deployed by NIOT with NCAOR (now NCPOR) in Arctic waters. It is not a radar, not a satellite, and not an Antarctic station. Confusing Arctic with Antarctic is a common trap. Only (d) is correct.