The correct flaw is (D): the argument "generalizes from a sample that is unlikely to be representative of public sentiment." This is true, and we see explicit support for it when the passage states that the survey respondents "see far more current movies than does the average moviegoer." This tells us that the respondents are not average, and therefore are not representative of the public.
(E) states that the argument "presumes, without justification, that the people surveyed based their responses on a random sampling of movies." Whereas (D) focused on the respondents, this answer choice is focusing on the movies the respondents have seen. The passage never explicitly makes this assumption, nor gives reason to believe it would be untrue. Even if it was proven to be true, (E) would not impact the passage as much as (D), so it is incorrect.
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