DocField Image and Fetch From?

I followed the documentation and set up a Doc which has Attach Image and Image. It is displaying the uploaded attachment with no problem. Let’s call this Doc ImageA.

Screen Shot 2023-05-28 at 9.57.52 PM

Now I have another doc DocA, which has a Image DocField, of which wanna reference Attach Image in ImageA.

Screen Shot 2023-05-28 at 9.58.09 PM

In order to display sample_attachment, which field should I fill in in DocA: Options or Fetch From?