Which of the following key permanently deletes a file from My Computer ?

The correct answer is (b) Shift + Delete.

When you delete a file using the Delete key, it is moved to the Recycle Bin. You can empty the Recycle Bin to permanently delete the files.

When you delete a file using Shift + Delete, it is permanently deleted without being moved to the Recycle Bin. This means that you cannot recover the file unless you have a backup.

Ctrl + Alt + Delete is a keyboard shortcut that opens the Task Manager.

Alt + Delete is a keyboard shortcut that opens the Windows Security dialog box.

I hope this helps!