Match the following : A- Maintenance control: B- Maintenance prediction: C- Maintenance process: 1-Cost of planning and scheduling hardware preventive maintenance, and software maintenance and upgrades, managing the hardware and software baselines, and providing response for hardware corrective maintenance. 2- Predicting the number of change requires a system understanding and the relationship between the system and external environment. 3- It is triggered by a set of change requests from system users, management or customers.