Why (E) option is incorrect?

'aim to' is wrong idiom, correct idiom is 'aim at'
Among A,B and C - IMO C

It must be a modifier modifying the previous clause.

I feel that the original sentence is correct.

E is wrong grammatically because has for several years.... should be followed by aimed at and as written above aim to is not correct.

B is incorrect because "to" used before improve is incorrect.

C is incorrect because "has followed a policy" should be followed by aimed at

D is incorrect because there is no modifier.

I agree with above user and his explanations. A is the right answer.

It has to be A!

i went with A because i could not find any issue with it

E is wrong because 'aim to' is incorrect idiom.

Look for parallelism between the logically similar terms : X and Y (X,Y must be parallel).

Only (A) and (E) sticks to the parallelism.

Problem with (E) :
The meaning of the sentence as per (E) changes to mean this :
The company followed a policy + The company followed this activity with the aim to ....
But if you look at the original sentence, the meaning is this:
The company followed policy X + Policy X is aimed at ....

Get it ?

HTH!