哪位帮忙解答一下：为什么C不对？我觉得从平行的角度来说，C更平行啊？（正确答案说是D）

40. To meet the rising marketing demand for fish and seafood, suppliers are growing fish twice as fast as their natural growth rate, cutting their feed allotment by nearly half and raising them on special diets.

A. their natural growth rate, cutting their feed allotment

B. their natural growth rate, their feed allotment cut

C. growing them naturally, cutting their feed allotment

D. they grow naturally, cutting their feed allotment

E. they grow naturally, with their feed allotment cut

 自己再加一点：growing them naturally 和 they grow naturally 虽然汉语意

思不一样，但是如果选C的意思，逻辑上我觉得也没有什么错吧？