In terms of word endings, English is simpler than some other languages such as Russian and German, as in its historical development it has dropped quite a few of its i affixes.

由于对地区经济的发展起着极其重要的作用，被人们形象地喻为经济发展的“先行官”的是（）

A．农业

B．工业

C．旅游业

D．交通运输