I think (B) and (D) can both be eliminated because of the "adverse effects" discussion. However, I eliminated it in a different way then simply saying that is not correct because "adverse effects" are not discussed.
The way that I see it is that the argument defines
the problem, consisting of two parts: (1) don't know which will is most recent and (2) don't know if last will has been found.
In (B), we don't care if there are any adverse effects to solving the problem or not. Maybe this system is extremely ineffective or maybe the Earth will implode if we do it. That doesn't matter. This is so because the conclusion is only about this one, particular, problem. It says "there would not be a problem to begin with." I think it would be different if the conclusion was "there would not be any problems."
In (D), we have basically the same thing.
(E) is not true. The information (that undated wills can create a problem for the executor) is available at the time of the action.
Matt, can you explain what you mean by this? I was reading (E) as saying that this
action (dating wills / stating what will it supersedes) would be based on the
information of the following: the date and knowledge of the previous will superseded. However, isn't (E) just basically restating the problem while the argument is actually stating the proposal will FIX the problem?