Final answer:
The correct command for a systems administrator to use in a scheduled task for a basic health check of systems outside of normal user hours is SFC (System File Checker). It is non-intrusive and can repair corrupted system files without disrupting operations.
Step-by-step explanation:
A systems administrator looking to create a scheduled task for performing a basic health check on systems during off-hours should opt for the SFC (System File Checker) command. This utility scans for and restores corrupted Windows system files, which is a crucial aspect of maintaining the integrity of an operating system. While CHKDSK checks the file system and file system metadata of a volume for logical and physical errors, it is more intrusive and may require a system to be offline. DISM (Deployment Image Service and Management) is used to fix the system image and Windows Component Store in Windows images. TASKLIST displays all running applications and services, which does not constitute a system health check. Therefore, the SFC command is the most appropriate for this task, as it can be run while the system is online without significant disruption to system operations.