OG168 关于double的词性问题的再次请教

168. Today, because of improvements in agricultural technology, the same amount of acreage produces double the apples that it has in 1910.

(A) double the apples that it has

(B) twice as many apples as it did

(C) as much as twice the apples it has

(D) two times as many apples as there were

(E) a doubling of the apples that it did

Choice B, the best answer, correctly uses the adverbial phrase twice as many... to modify the verb produces; properly employs many rather than much to describe a quantity made up of countable units (apples); and appropriately substitutes did for the understood produced to express the logically necessary past tense of produces.
                Choice A awkwardly substitutes the adjective double for twice;
                uses that without a clear referent; and misuses has to refer to events occurring in 1910. Choice C employs the incorrect much in a wordy construction and also misuses has. D is wordy and imprecise;... as there were in 1910 refers to all apples produced in 1910, regardless of location. E is illogical: since that refers to a doubling, E nonsensically asserts that the doubling occurred in 1910.

一路看168题的帖子下来，发现前人NN们讨论聚焦的焦点都是关于that的指代问题。很感激NN们的解答，使得我对于that指代的了解更加清晰。我对于答案无异议。

但关于double仍有一些小疑问。

double既可以做动词，也可以做形容词，在这里A选项中的double肯定不是作为动词的，OG11中解释里的第一句话就是the adjective double cannot modify the verb produces, only an adverb（twice）can modify a verb.我的问题是double不可以作为形容词去修饰the apple吗？为什么要修饰produce?

实在困惑，请指教！

非常感谢楼上的详细解答。

其实我是有在哪里看到过double the sth做形容词的用法，不记得是GWD还是PREP了，但是刚刚简单搜了一下，没有搜到。也许是我记错了吧。

thank you again