Final answer:
To improve disk efficiency by reorganizing files, you should use the Optimize Drives utility in Windows, which was formerly known as Disk Defragmenter.
Step-by-step explanation:
To reorganize the files on your disk to improve efficiency, you should use the Optimize Drives utility. This tool, previously known as Disk Defragmenter, optimizes the files on your hard drive to ensure that they are stored in contiguous blocks. By doing so, it can potentially speed up access times to those files as it reduces the amount of movement the hard drive's read/write head has to make. The other options you have listed serve different purposes: Disk Properties provides information about the disk, Disk Cleanup helps to free up space on your hard drive by removing unnecessary files, and Disk Checker scans the disk for file system errors. The correct choice for reorganizing files for efficiency is c) Optimize Drive.