D is a chronological event. The War Memorial was created where, how and maybe why. The maybe why is only about why Washington was chosen.
B again is recounting exactly how the peace was brought about in korea in the 1950s. It's not a positional paper.
A is not a position although it could be made into one. This question is a bit ambiguous and you are forced to choose between A and C. I would pick C because it is a position. No matter what else is relayed, the thing you must determine is that the Dental Association has a position: prevention.
A cannot be so easily dealt with. The problem is that it has a position, but it looks like it does not have any kind of resolution. It's intent is to show that antibiotics have an effect on the food chain. If it said a "good" effect or a "bad" effect, it would be a shoo in.
Answer C <<<<< But don't be surprised if it is A nevertheless.
