C. Disk Cleanup
Disk Cleanup helps to free up disk space on the hard drive by removing unnecessary files such as temporary files, system files, and recycle bin contents. By running Disk Cleanup, the technician can potentially improve the performance of the PC by clearing out unnecessary files that may be causing the slowdown.
Disk Defragmentation (option B) is useful for optimizing the layout of files on the disk, but it may not directly address the issue of slow loading programs and files if the primary concern is disk space rather than fragmentation.
Disk Management (option A) and Device Manager (option D) are not directly related to disk cleanup or optimizing disk performance. Disk Management is used for partitioning and formatting disks, while Device Manager is used for managing hardware devices.