None of the above - I'd explain why I think the way the code was written was problematic (e.g. function logic can't easily be readily comprehended in one go, co

None of the above - I'd explain why I think the way the code was written was problematic (e.g. function logic can't easily be readily comprehended in one go, consider how you could break this down). But to a large degree my "tone" and level of detail would depend on the seniority of the author.