Helm multi-selection pre select multiple candidates

Question

I have a helm source:

(setq helm-source
  `((name . "My source")
    (candidates . ("Option 1" "Option 2" "Option 3" "Option 4"))
    (action . (lambda (candidate) (helm-marked-candidates)))))

And later get the selected options like this:

(setq result (helm :sources '(helm-source)))

I want that "Option 2" and "Option 3" are already marked in the same way I could mark them with C-SPC.