External command in DOS are A. Copy, edit, sys, format B. Edit, sys, chkdsk C. Chkdsk, prompt, date D. Sys, ver, vol

The correct answer is: A. Copy, edit, sys, format

External commands are commands that are not stored in the DOS memory. They are stored on disk and are loaded into memory when they are needed. Some common external commands are:

• Copy: Copies files from one location to another.
• Edit: Edits text files.
• Sys: Creates a system disk.
• Format: Formats a disk.

The other options are not external commands.

• Option B: Edit, sys, chkdsk

Edit is an internal command. It is stored in the DOS memory and does not need to be loaded from disk. Sys is an external command, but chkdsk is an internal command.

• Option C: Chkdsk, prompt, date

Chkdsk is an internal command. Prompt is an internal command. Date is an external command.

• Option D: Sys, ver, vol

Sys is an external command. Ver is an internal command. Vol is an internal command.