Which of the following countries researchers have discovered triple AGN, recently?

Which of the following countries researchers have discovered triple AGN, recently?

A. US

B. China

C. India

D. Japan

Explanation:

Indian researchers have discovered three supermassive black holes from three galaxies merging together to form a triple active galactic nucleus in our nearby universe. The study was published as a letter in the journal Astronomy and Astrophysics. They are called active galactic nuclei (AGN) and release huge amounts of ionized particles and energy into the galaxy and its environment. Both of these ultimately contribute to the growth of the medium around the galaxy and ultimately the evolution of the galaxy itself. Many AGN pairs have been detected in the past, but triple AGN are extremely rare, and only a handful has been detected before using X-ray observations.