What type of program is used to organize the structure of a disk?

The correct choice is that a disk utility program is designed specifically to organize the structure of a disk. Disk utilities can perform various tasks related to the management of disk drives, which include creating, deleting, and formatting partitions, as well as checking and repairing filesystem errors. They help in structuring how data is saved and accessed on the disk, contributing to efficient data retrieval and storage.

Defragmentation, while it has the role of reorganizing fragmented data on a disk, does not fundamentally organize the structure of the disk itself. Rather, it enhances the performance of the disk by rearranging pieces of files to be stored in contiguous spaces, which can speed up access times but does not address the overall organization of disk partitions and formatting.

File management refers to the methods and processes used to store, retrieve, and organize files within the operating system but doesn't inherently involve the structure of the disk itself. Disk cleanup involves freeing up space on a disk by removing unnecessary files but does not relate to the structural organization of the disk. Thus, a disk utility program is indeed the correct answer for organizing the structure of a disk.