SAT Text Structure and Purpose Question

The Ionian Mission, first published in 1981, is a novel in Patrick O'Brian's Aubrey: Maturin series, which includes twenty completed books. Some critics have found fault with the abrupt endings of The Ionian Misston and other books in the series, saying that they do not finish conclusively but arbitrarily stop. But other critics argue that the books should not be thought of as discrete texts with traditional beginnings and endings but as a single incredibly long work, similar to other multivolume stories, such as Marcel Proust's In Search of Lost Time. Which choice best states the main purpose of the text?