请教一下but和while的区别

superfanluyao

附一道例题  球讲解
223.(30372-!-item-!-188;#058&005388)(GWD-23-Q23)



After several years of rapid growth, the health care company became one of the largest health care providers in the metropolitan area, while it then proved unable to handle the increase in business, falling months behind in its payment to doctors and hospitals.

A. while it then proved unable to handle the increase in business, falling months behind in its payment to

B. while it then proved unable to handle the increase in business and fell months behind in its payment to

C. but then it proved unable to handle the increase in business, falling months behind in its paying

D. but then proving unable to handle the increase in business, falling months behind in paying

E. but then proved unable to handle the increase in business, falling months behind in paying

答案没问题 只想知道  能否一开始就排除 while  这两个词的区别到底是什么呢？ 求解答

superfanluyao

自己先顶一个。。。