Ethically questionable acts (such as failing to reveal all bad consequences of one’s policies) can sometimes be justified by their good consequences (such as helping to get one elected, thereby helping to implement a positive policy agenda). (A) helps connect the benefits of getting elected to being justified in failing to reveal all of the bad consequences of one’s policies.

(B) arguably undermines the argument, since it would have us prefer failing (not getting elected) over succeeding (getting elected) through unethical measures (not being completely honest).

(C) arguably undermines the argument, because it would have us conclude that obtaining a legitimate end (getting elected) actually becomes illegitimate (unjustified) if it’s obtained through illegitimate means (failing to be completely honest).

(D) doesn’t speak to whether one can be justified in a certain action. Although (D) supports the idea that a candidate who isn’t trusted can still accomplish their agenda, we want to support a conclusion that getting elected through being less than completely honest can be justified.

(E) suggests that it might be better to let voters know the whole truth. But we’re trying to justify hiding some information from voters.