Answer : 4. "A high speed expendable air target"
Explanation :

Defense Research and Development Organization (DRDO) has recently successfully conducted four flight trials of 'Abhyas', a high-speed expendable aerial target. Developed by DRDO's Aeronautical Development Establishment, the exercise serves as a realistic threat scenario to practice weapon systems and validate armed forces equipment for air attack. It features an autonomous flight design, an indigenously built autopilot and a laptop-based ground control system for integration and analysis.