This is exactly what Louis overlooks. His whole argument goes like this: "If we believed intentions were mostly bad, terrible things would happen (we'd lose trust, society would fall apart). So intentions can't be mostly bad." But (A) points out the problem: just because believing something would cause harm ("deleterious") doesn't mean the belief is wrong. A belief can be true and harmful to accept at the same time.

(B) accuses Louis of assuming that if two things can't both be true, then they can't both be false either. But what are the two things that can't both be true? It's difficult to match up anything from the stimulus. In addition, how does Louis think two things can't both be false? Or in other words, how does he think that if one thing is false, another thing must be true? Louis doesn't start with the idea that one thing is false and try to conclude that something else must be true. Rather, he argues against one claim (intentions are mostly bad) based on the consequences of believing it.

(C) describes a situation where someone attacks the people making an argument instead of the argument itself. For example, "You only say that because you're trying to sell me something" is this kind of attack. But Louis never questions why anyone might believe intentions are mostly bad or accuse them of having suspicious motives. His argument is purely about what would happen if we believed it, not about who believes it or why they believe it.

(D) says Louis assumes the most negative outcome will "inevitably occur." You might connect this to Louis's claim that we'd "inevitably" lose trust if we believed intentions were mostly bad. But we can accept that claim as a premise. There's nothing wrong with Louis saying that believing intentions are mostly bad would lead to a loss of trust and threaten society. That chain of events is reasonable enough, and it's not where the argument goes wrong. The problem is what Louis does with that chain of events. He uses it to conclude that intentions can't be mostly bad, as if bad consequences of believing something prove the belief is false. (D) doesn't identify that flaw.

(E) describes a situation where someone observes something about one group of people and then assumes it's also true of a different group. But Louis doesn't do this. He's making a single general claim about people's intentions. He isn't studying one group and then applying his findings to another group.