Here's the OG explantion to this question:
The best choice, A, offers an adjective phraseunequivocally modifying policy and exhibiting grammatical parallelism (decreasing... and improving). In choice B, the gerund the decreasing is not grammatically parallel with the infinitive to improve. Likewise, in C and D, the decreasing of... costs is not parallel with improving the efficiency. In E, the infinitives to decrease and to improve, while parallel, are less idiomatic than the prepositional phrase of decreasing... and improving in modifying the noun aim. Also, with the aim... improve can easily be construed as referring to the Baldrick Manufacturing Company and so does not refer unequivocally to policy.
I have a question about this explantion. OG says "with the aim... improve can easily be construed as referring to the Baldrick Manufacturing Company and so does not refer unequivocally to policy" but I think it is exactly referring to "the company". The latter part of the sentence is " the efficiency of its distribution system." , if we choose A, then the choice is modifying "policy", but obviously its refers to “the company" rather than "policy". So I think E is the better choice.
Plus, "aim to" and "aim at" are both suitable here. This is the explantion from Longman:
(aim)
*to try or intend to achieve something
1.aim to do sth
　 We aim to finish by Friday.
2.(be) aimed at doing sth
　 an initiative aimed at reducing road accidents
*to choose the place, person etc that you want to hit or reach and point a weapon or another object towards them
　 Denver aimed his gun but did not shoot.
aim at/for
　 The pilot was aiming for the runway but came down in a nearby field.
Can someone please explain why A not E? Thank you.
