Please explain how to solve this one

Thank you for your question. These types of questions - flawed parallel reasoning - do not necessarily call for diagramming for proper solution. On this question, for example, I would not diagram, but instead look carefully at the terms of the stimulus. The flaw generalizes from part to whole - although the various goods sold at food co-ops may be generally cheaper than the same goods sold at grocery stores, this does not mean that overall it is more economical to shop at food co-ops. Likewise, the correct answer choice here engages in the same flawed method of reasoning. Just because each part (each bicycle) has a certain quality does not mean that we can aggregate as has been done in this answer choice. Hope this helps! Please let us know if you have any additional questions.

Hi! I'm still a little lost on this. If store (A) is a co-op and has the same items at a less expensive price than store (B) (C) or (D), why can't we extrapolate that it is more economical to shop there? I could understand if it said it has some items cheaper, but it seems to indicate that all items are cheaper? Thanks for any clarification!

I will add that I am seeing how the LSAT questions are a closed universe. The conditions exist in a vacuum. Our opinions have been shaped to see a food co-op and saving as a good thing. But if the LSAT says it's FLAWED then by gawd accept the argument is flawed no matter how lovely you think co-ops are in real life. Otherwise you and me will go. What? it's flawed...nah I buy good stuff at a co-op. LSAT could care less what you experience in life is, what matters is what the questions present.