一道700分的简单题prep1,82

each year companies in the US could save as much as $58 billion annually by preventing illness among employees and gain as much as $200 billion through inproving performance of workers if they simply provided offices with cleaner air.

D in employee illness prevention and gain as much as $200 billion through improving performance of workers if they simply provided

E by preventing illness among employees and gain as much as $200 billion through improved worker performance if they simply provided

答案选E，说 e里面的improved比d里面的improving 更符合逻辑，我就纳闷了哈，本来那个companies做主语，正好是improving 主动提高performance,怎么就不符合逻辑了呢？？