对答案有困惑，求高人指点OG-CR-14

In Washington County,attendance at the movies is just large enough for the cinema operators to make modest profits.The size of the county's population is stable and is not expected to increase much.Yet there are investors ready to double the number of movie screen in the country within five years, and they are predicting solid profits both for themselves and for the established cinema operators.
which of the following ,if true about Washington Conunty,most helps to provide a justification for the investor's prediction?

答案是A：over the next ten years,people in teenage years,the prime moviegoing age,will be a rapidly growing proportion of the county's population.

题目中说5年内加倍屏幕数量，可是A忠却说的是在接下来的10年中去看电影的人会很快增加。

E The sale of snacks and drinks in cinemas accounts for a steadily growing share of most cinema operators' profits.这个选项也可以解释利润的增长啊？有些迷惑求高人解释下