Answer : 4. "Russia"
Explanation :

India, China and Iran have set up pavilions at the 9th International Military-Technical Forum, Army 2023, hosted by Russia. The India Pavilion has stalls from the Defense Research and Development Organization (DRDO), and three Defense Public Sector Undertakings including Bharat Electronics Limited (BEL), Bharat Earth Movers Limited (BEML), and Goa Shipyard Limited (GSL).