Copy and Xcopy are same in the sense

In Disk Operating System (DOS), both Copy and Xcopy commands can be used to copy files or groups of files. However, they differ in their functionalities:

Copy is an internal command of DOS, which means it is built into the command interpreter (command.com) and does not require a separate executable file.
Xcopy, on the other hand, is an external command of DOS, which means it is implemented as a separate executable file (xcopy.exe). It provides more advanced features compared to the basic Copy command, such as copying subdirectories recursively, copying hidden/system files, and verifying copied files.

Therefore, the correct answer is Option D: Both a and b.