Which command is used to display a list of deleted files that DOS can undelete?

Answer: Option C

The undelete command in DOS is used to recover accidentally deleted files.
/list option with undelete displays a list of files that have been deleted and are available for recovery.

This command helps users identify which files can be restored to their original state before permanent deletion.

Undelete .:
This syntax is not the correct way to list deleted files. It suggests attempting to undelete all files, which is not how the command operates.

Undelete/all:
There is no /all option for the undelete command in DOS. This option does not exist.

None of the above:
This option is incorrect because Undelete/list is a valid command in DOS to display a list of deleted files.

Therefore, the correct answer is Option C: Undelete/list.