Hey lyujen,
Thanks for the question, and welcome to the Forum! Let's break down the logic in this question and see if we can figure out exactly what the author's thinking.
Since this is an Assumption question, we can expect one of two things to happen: either there will be a missing piece of information needed to connect the conclusion to the rest of the premises (a Supporter Assumption), or there will be an idea that could severely harm the argument and the correct answer choice will rule it out (a Defender Assumption).
This is a Supporter Assumption, where the conclusion contains a new idea—in this case that "producers are never obligated to reveal product defects to consumers"—that needs to be linked back to the information in the premise that "the only obligation that all parties [producers and consumers] have is to act in the best interests of their own side." (sidenote: I LOVE Supporters, as you can often make incredibly strong prephrases about the correct answer)
So the first big hint I can give you here is that once you spot that "new" idea in the conclusion (that producers are not obligated to reveal product defects) you can trust that it MUST appear in the correct answer choice. You simply cannot have an untethered or rogue piece in the conclusion when you're trying to help an argument! And considering that only answer choice (A) talks about producers revealing product defects, right away you can know that that answer is correct. Not all Supporter Assumptions will be that straightforward, but a lot of them, particularly those in the first half of an LR section, can be solved by such a method
The conditionality in the first sentence, with "only" as a huge clue, is notable and I'm pleased to see that you spotted it! Basically what that statement tells you is that consumers and producers have just one obligation: to act in their own best interests. So if something is in their best interests they are required to act on it. In this case, we're told that revealing product defects is in the best interest of the
consumer, so we can conclude, and in fact are told explicitly, that consumers are always obligated to report those defects.
Producers, on the other hand, are "never" obligated to report defects. Think about what the author would have to believe to conclude that. What must be true for producers and defects, if producers have no obligation to report them? It must be the case that reporting/revealing defects is not ("never") in the
best interest of those producers!
And that's exactly what answer choice (A) tells us. (E) has nothing to do with producers reporting defects and whether that's in their best interests or not—it simply says consumers' and producers' best interests don't coincide, which is much broader and more extreme than what we need here—so it cannot be an assumption at the heart of the argument.
I hope that helps! Thanks again!
Jon
