Answer : 4. "राष्ट्रीय सुरक्षा परिषद सचिवालय"
Explanation :

Solution: India National Cyber Security Exercise (NCX) 2023 was hosted at SCOPE Convention Center in New Delhi. The exercise was jointly conducted by the National Security Council Secretariat (NSCS) and the National Defense University (RRU). This was the second edition of the National Cyber Security Exercise. Apart from this exercise, India NCX 2023 also hosted the India NCX CISO Conclave. More than 200 Chief Information Security Officers (CISOs) participated in it.