Correct Answer: (b) Scramjet combustor The Defence Research and Development Organisation (DRDO) has achieved a significant milestone by successfully conducting a ground test of an advanced scramjet combustor. Developed by the Defence Research & Development Laboratory (DRDL) in Hyderabad, this technology is integral to next-generation hypersonic missiles. The scramjet combustor demonstrated stable combustion and successful ignition during a 120-second test, marking a breakthrough in hypersonic propulsion systems for operational use.