英文句子理解問題= =怎麼都搞不懂這其中的邏輯

題目：

英文句子理解問題= =怎麼都搞不懂這其中的邏輯
Since choices A and B did not contain the word "only" after "applies" so that the law might apply to both the long run and the shot run, the answer to the question has to be A or B. In other words, the law of diminishing returns must apply to either the short run or the long run.
前面明明說兩者都有可能,後來怎麼又變成不是A就是B了呢_ _

解答：

因爲A與B在applies後面都未包含only,因此答案只能是A或B.
你沒看懂.
再問： so that the law might apply to both the long run and the shot run 既然long run和short run都有可能，爲什麼答案確定是兩者之一而不是兩者都對呢？
再答： 建議把整段全貼上來，大家一起看看。