Sentence Correction

Each year companies in the United State 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

Sentence starts with each year again we don't need to use annually so that rules out A, B and C

D - in employee illness prevention, through improving performance of workers - wrong

IMO E.

IMO E.

In A,B & C the usage of "annually" is redundant as "Each year" means the same.
and D alters the meaning of original sentence with save as much as $58 billion in employee illness prevention.

OA please.

IMO : E.

A - Redundant. are there any other issues here?
B - Redundant. Not parallel and through worker performance improved -- does not sound right
C - Redundant.. through worker performance improved -- does not sound right
D - Not parallel.
E - redundant word Annual word is removed and sentence is parallel.

OA is E

A typical modifier and parallelism question that is asked in the GMAT>>>>>