Each year companies in the United States could save as much as $58 billion annually by preventing
illness among employees and gain as much as $200 billion through improving performance of
workers if they simply provided offices with cleaner air.
(A) annually by preventing illness among employees and gain as much as $200 billion through
improving performance of workers if they simply provided
(B) annually if they prevented employee illness and gain as much as $200 billion through worker
performance improved by simply providing
(C) annually in employee illness prevention and gain as much as $200 billion through worker
performance improved by simply providing
(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
Ans:E
what difference about use "improving performance" and " improved performance " to express setence of meaning ??