Official Explanation
In this argument, we have the conclusion that 3-D films make more money than 2-D films, based on the evidence that they are more popular. To find the assumption that makes this argument work, we have to identify what’s missing to link the evidence to the conclusion. Here, (E) is the best answer, as it correctly creates the link between high popularity and high earnings that the given evidence and conclusion assume.
(A) is concerned with the content of the films themselves. If an answer choice like this tempts you, evaluate whether it would still make sense if you replaced 3-D and 2-D films with other types of products--oranges and apples, for example. If you’ve identified the correct assumption, this shift in content shouldn’t matter as long as the products make sense in context. Here, content is irrelevant to the assumption.
Similarly, the ability to make 3-D films (B) or the ease with which these films are made (C) doesn’t have anything to do with the link between popularity and revenues that the conclusion and evidence demand.
(D) may be tempting, because it makes sense that the most popular films were 3-D if most films were 3-D, but it still does not engage on the issue of price, which is vital to making the assumption that the most popular films make the most money.
Answer: (E)