Abridged, complementary. Certain “versions of novels and essays” cut out important parts, or “excise essential elements.” Then, “to fully understand the intent of the original,” students would have to “supplement,” or add to, “their reading with [some type of] sources.” So the text versions described by blank (i) are lacking parts of the original and the reading sources described by blank (ii) provide some of what is lacking. An “abridged” source is one that has been shortened, and “complementary sources” would enhance or support this shortened version. Be careful of the homophone “complimentary,” which means either admiring or given free of charge, neither of which works in blank (ii). “Compelling” sources would either evoke interest or inspire conviction. While the supplemental reading might do so, no indication of either additional meaning is given in the sentence, and this choice fails to address the problem that “abridged versions” create for students. “Annotated versions” have additional notes of explanation; such versions would be less likely to require supplementation to understand, not more. Finally, there is no indication that the “[ blank (i)] versions of novels and essays” are “antedated,” or dated prior to their actual date.