Explanation:

• A recent study said that the Indian Astronomical Observatory (IAO) located at Hanle near Leh in Ladakh is becoming one of the promising observatory sites globally. This is due to its advantages of more clear nights, minimal light pollution, background aerosol concentration, extremely dry atmospheric condition, and uninterrupted by monsoon. IAO is is operated by the Indian Institute of Astrophysics, Bangalore. The IAO currently hosts Telescopes such as the Himalayan Chandra Telescope, GROWTH-India Telescope, High Altitude Gamma Ray Telescope. Hence option 4th is correct.