assuming without giving justification that the outdoor advertising increased market share by some means other than by diverting
Why this is right
This is also presenting a supposed Necessary Assumption. Do the merchants need to assume that outdoor advertising increases market share by some means other than by diverting trade from competing businesses? That's a mouthful. Let's see if negating this answer would weaken: Outdoor advertising only increases market share by diverting trade from competing businesses That does weaken, but it's not likely to 'click' for most people, unless they picked up on a weirdness to the argument (unrelated to the Famous correlation = causation flaw). Penglai, we are told, is an isolated island. Some people live there and probably don't leave much, since it's expensive to go back and forth to an isolated island. Some people may travel there for vacation. The merchants' conclusion is worried about the "overall volume of business" that gets done in Penglai. Maybe in 2020, $2 billion worth of transactions occurred. How would eliminating outdoor advertising change that? If you live on the island, you're still spending the same amount of your income on necessities and luxuries, whether businesses have an outdoor ad or not. If you're a tourist visiting, you're still spending the same amount of your vacation budget there. You showed up ready to blow $1000 during your week in Penglai. That's the volume of business you're creating. If there are outdoor ads for certain places, you might be more likely to spend your money at that restaurant rather than at some other restaurant that doesn't have an outdoor ad, but if we take away these outdoor ads, you're still going out to dinner at some restaurant. The idea is that outdoor ads are more likely to affect where you spend your money than they are to affect whether you spend your money. The merchants are acting like if there aren't outdoor ads, then people just won't take out their wallet as much. When we negate the assumption in this answer choice, we are objecting, "What are you talking about? Sure, outdoor ads can help a business gain bigger market share. But that's not be cause outdoor ads create sales that wouldn't otherwise exist. The same volume of money is going to be spent either way. Outdoor ads just funnel money more towards the advertised businesses than towards non-advertised businesses."
Skill tested: Flaw · how this choice captures the argument's function is the move to repeat next time.