Please Explain...

Hi, A weakens the argument by providing us a reason not to list every single interaction. If we list 1000 interactions, 2 of which are fatal and 998 of which are minor, A would show that listing everything might lead to more deaths with minimal added benefit. D is not really relevant to the argument. If it were true, it might mean that there are as of yet unidentified interactions, but the argument has absolutely nothing to do with unknown interactions. It is explicitly only about known interactions