CHKDSK can be used to find

Answer: Option A

In Disk Operating System (DOS), the CHKDSK command is used to find and repair disk errors, including locating bad sectors on the disk. Therefore, the correct option is Option A: Disk’s bad portion. CHKDSK analyzes the file system for errors, checks the disk surface for physical errors (bad sectors), and ensures the integrity of file and directory structures.

Option B, "Occupied space," and Option C, "Free space," are not functionalities of CHKDSK. CHKDSK primarily focuses on disk integrity and error-checking rather than space allocation.

Therefore, the correct answer is Option A: Disk’s bad portion.