The magnetic observatory which was inaugurated on 30 th March 2015 is located at

The correct answer is D, Port Blair.

A magnetic observatory records variations in the Earth's magnetic field over time. That data feeds into geomagnetic research, navigation, and space weather monitoring. The observatory inaugurated at Port Blair in March 2015 was set up under the Indian Institute of Geomagnetism, which runs India's network of such observatories.

• Allahabad (A): It has an older geomagnetic observatory, so it is not the facility inaugurated in 2015.
• Gulmarg (B): Kashmir is known for its high-altitude setting, but this inauguration was not held there.
• Shillong (C): Meghalaya hosts other geophysical institutions, but not this observatory.

Core concept: Earth's magnetic field and geomagnetic observatories. The Andamans location adds coverage in a near-equatorial sector, which is useful for studying the field. For Mains, this connects to space weather effects on satellite communication, aviation and power grids.

Trap: Candidates often pick Alibag or Allahabad because they are the better-known older observatories. Treat the 2015 inauguration date as the clue, not the age of the institution.