Understanding the argument -
Naomi: One critical interpretation of an artwork is superior to another if, all other things being equal, it accounts for more aspects of that work. For example, accounting for a work's style and content is superior to accounting for only its style. - Think of a comparison between A and B; the superior would be the one with all the qualities of the other and much more. This interpretation takes into account the quality and quantity.
Harold: But you're leaving out an essential element: the quality of the interpretation. It's ridiculous to suggest that simply addressing more aspects of a work is a mark of superiority. - Harold assumes that Naomi doesn't consider quality and that he takes quantity into account, but that interpretation is wrong. Naomi takes both into account.
Harold's response is most vulnerable to the criticism that it
(A) does not offer a counterexample to disprove Naomi's claim - We can still criticize without a counterexample. Wrong.
(B) mischaracterizes Naomi's argument in the guise of restating it - Yes. While inferring Naomi's argument, Harold hides that Naomi already considers quantity and quality. He misleadingly persuades the reader that Naomi misses it, but Naomi, in reality, didn't miss that.
(C) fails to consider that Naomi may have additional criteria in mind - No additional criteria are mentioned in Naomi's argument.
(D) fails to establish that the quality of an interpretation can be ascertained - in simple English, it means "fails to establish that the quality of an interpretation can be measured or validated." Whether or not the quality can be measured somehow is not an issue. The real issue is that while Naomi implicitly considered both quality and quantity, Harold conveniently assumed that he didn't consider quality.
(E) claims that Naomi's reasoning leads to an absurd conclusion when taken to an extreme - no.