Recently, scientists observed the merger of giant 'blackholes' billions of light- years away from the Earth. What is the significance of this observation?

1. A

   ‘Higgs boson particles’ were detected.

   (a) Higgs boson particles were detected at the LHC in 2012, not by watching distant black-hole mergers. Not the key.

2. B

   ‘Gravitational waves’ were detected.

   (b) Gravitational waves. LIGO’s 2015 (announced 2016) detection, and later events, were from merging black holes billions of light-years away. That is the official key.

3. C

   Possibility of inter-galactic space travel through ‘wormhole’ was confirmed.

   (c) Wormhole inter-galactic travel was not confirmed by those observations. Not the key.

4. D

   It enabled the scientists to understand ‘singularity’.

   (d) Singularity inside a black hole remains a theoretical region; merger detections do not “enable understanding of singularity” as the keyed significance. Not the key.

Summary. Official key is (b). Binary black-hole mergers are the source of the gravitational waves LIGO/Virgo detected. Higgs, wormholes and singularity are other physics stories. Honour (b).