Which of the following is an example of periodic maintenance of a computer system?

Periodic maintenance of a computer system is essential for ensuring that the system operates efficiently and reliably over time. System backup is a key component of this maintenance because it involves regularly creating copies of data and system configurations to protect against data loss due to hardware failures, software issues, or other unforeseen events. By performing system backups at regular intervals, users can safeguard their information and restore the system to a previous working state if needed. This practice helps to maintain data integrity and provides a safety net against potential problems.

Hardware installation, software upgrades, and network configurations, while important tasks, typically fall outside the scope of periodic maintenance, as they are generally one-time setups or modifications rather than routine checks or updates intended to maintain the system's ongoing performance.