题型分类：文章总结题

题干分析：选择概括性的正确选项。

选项分析:

C 选项是第二段和第三段的重要信息。 The protectionist hypothesis is that extrafloral nectar attracts ants, and that the ants, in order to preserve this energy-rich food source, attack insects that might harm the plant 对应第二段 Since the highly active worker ants require a great deal of energy, plants exploit this need by providing extrafloral nectar that supplies ants with abundant energy. To return this favor, ants guard the nectaries... 以及第三段 This view and the opposing “protectionist” hypothesis that ants defend plants, and since then many more observations and experiments have provided still further proof that ants benefit plants。

D 选项是第三段、第四段和第五段的重要信息。这三段都是在举例说明蚂蚁保护分泌花外蜜植物的证据。

E 选项是第五段的重要信息。对应第五段 Bentley compared the seed production of six plants that grew where there were no ants with that of seventeen plants that were occupied by ants. Unprotected plants bore only 45 seeds per plant, but plants occupied by ants bore 211 seeds per plant.

A 选项说进化史表明分泌花外蜜的植物起源于热带。此信息不是文中主要信息。

B 选项说花外蜜比花蜜有更高的糖分，从而更吸引蚂蚁和其他昆虫，文中无此比较，为无中生有。

F 选项说 Ants generally ignore small insects，蚂蚁忽略小昆虫的信息文中没有提及，属于无中生有。