The Baldrick Manufacturing Company has for several years followed a policy aimed at decreasing operating costs and improving the efficiency of its distribution system.
(A) aimed at decreasing operating costs and improving
(B) aimed at the decreasing of operating costs and to improve
(C) aiming at the decreasing of operating costs and improving
(D) the aim of which is the decreasing of operating costs and improving
(E) with the aim to decrease operating costs and to improve
不好意思,我又來問問題了

請教各位高手
答案是A,但為什麼用aimed而不是aiming呢?
原句還原難道不是a policy which aims at...
