Small as it is,the ant is as much a creature as ____ all other animals on the earth.(are)

蚂蚁虽小，但作为一个生物来说，它们和地球上所有动物一样重要。
这个其实是部分倒装了,本来为all other animals are ,把are 前提,由于animals是复数,所以选A不选B。
as...as意为\"和……一样\"，表示同级的比较。使用时要注意第一个as为副词，第二个as为连词。其基本结构为：as+ adj./ adv. +as。例如：
(1)This film is as interesting as that one.这部电影和那部电影一样有趣。
(2)Your pen writes as smoothly as mine.你的钢笔书写起来和我的一样流畅。
其否定式为not as/so +adj./ adv. +as。例如：
This dictionary is not as/so useful as you think.这本字典不如你想象的那样有用。
若有修饰成分，如twice, three times, half, a quarter等，则须置于第一个as之前。例如：
Your bag is twice as expensive as mine.你的袋子比我的贵一倍。