Copyright rests with the publisher (Embargo or open access)

If a chapter from your thesis has already been published as an article, you may have transferred the copyright to the publisher. In that case, please consult the contract with the publisher to check whether it contains any provisions regarding the reuse of material for the purposes of a thesis and its publication.

If the contract does not specify this, please consult the Open Policy Finder.

If a chapter from your thesis has already been published in an Open Access journal, no embargo is required on that chapter, and possibly not on the entire thesis either.
Under point 2 in the licence form, you can indicate which option applies.