the apparent ineffectuality of legislative representatives is the only source of popular dissatisfaction
Why this is right
This is harsh sounding, for a Necessary Assumption answer, but it's also conditional, so we want to look at it as a reasoning move and see if it feels like the author made that move. "The only" is weird indicator, because it's actually a Left side (sufficient) indicator. Famously, "only / only if" are Right side (necessary ) indicators. The only is the only time you'd ever put 'only' on the left, if that dumb mnemonic helps. So this answer is saying, If there's a popular source it's about their of dissatisfaction with ? apparent legislative representatives ineffectuality The author's conclusion begins with the trigger on the left. "Whenever people complain about their reps ...", and the evidence only talks about the complaint of ineffectuality. The evidence establishes if the complaint is the reps are about ineffectuality ? doing what we elected them to The conclusion is claiming, if there's the reps are a complaint - - - - - - - - - - ? doing what we elected them to So the argument is missing the link being offered by this answer choice: if there's the complaint is a complaint ? about ineffectuality Alternatively, we could judge this answer by negating it. If we said, "There are other sources of dissatisfaction besides the apparent ineffectuality of reps", would that weaken? Yes! That would be taking us into our Objection zone of, "What about when we are popularly dissatisfied that our representatives are personally enriching themselves by making deals with foreign leaders? What about when are leaders say violent or offensive things?"
Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.