After several years of rapid growth, the healthy 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.

1. while it then proved unable to handle the increase in business, falling months behind in its payment to
2. while it then proved unable to handle the increase in business and fell months behind in its payment to
3. but then it proved unable to handle the increase in business, falling months behind in its paying
4. but then proving unable to handle the increase in business, falling months behind in paying
5. but then proved unable to handle the increase in business, falling months behind in paying

答案为E,我选了B,请帮忙解释

正确的应该是E.答案里省略了主语the healthy care company, 所以后面的动词

prove是和前面的动词became并列的谓语,全句应该是the healthy care company became.......but then proved unable to......, falling months behind.......

prove可以作为不及物动词意思是to be found or shown,所以这句话也可以改写成the healthy care company was found/shown unable to.....,比如可以说 a guess that proved right. 有人同意么