Prep08的题 求NN来品一品句子结构！万分感谢！

小灰灰养大鸟

For thefarmer who takes care to keep them cool, providing them with high-energyfeed, and milking them regularly, Holstein cows are producing an average of2,275 gallons of milk each per year.

A.       providingthem with high-energy feed, and milking them regularly, Holstein cows areproducing

B.       providingthem with high-energy feed, and milked regularly, the Holstein cow produces

C.       providedwith high-energy feed, and milking them regularly, Holstein cows are producing

D.      provided with high-energy feed, andmilked regularly, the Holstein cow produces        (E)

E.       provided with high-energy feed, andmilked regularly, Holstein cows will produce

求各位大侠教一下我，这个句子里的For是起到什么作用啊？是对...来说吗？还是因为（那后面只跟了一个n farmer，可以吗？）

万分感谢！