Which of the following is a key activity in the operational Process?

Using the system for operations is indeed a key activity in the operational process. This step involves deploying and utilizing the system in real-world scenarios to meet its intended purpose. It reflects the culmination of the systems engineering lifecycle, where theoretical designs and validation efforts translate into practical application.

This activity is crucial as it ensures that the system functions as expected and delivers value to users and stakeholders. It also allows for real-time feedback and data collection, which can inform future improvements or modifications to the system. By engaging with the system in its operational environment, organizations can assess its effectiveness, efficiency, and overall performance in achieving operational objectives.