It sounds like you’re approaching these questions the right way- certainly there can be more than one flaw in an argument, but if there is, only one of those flaws will show up in the answer choices. For example, in this argument there is also an assumption (which I think you picked up on) that the nationwide system would indeed provide timely access to the specialized trauma centers. However, (i) this assumption doesn’t show up in any of the answer choices; and (ii) it’s not as directly connected to the main conclusion as is the assumption that if more lives are saved, more money will be made as a result. For even if the nationwide system would indeed provide timely access, the conclusion still doesn’t follow.