Not only are you allowed to make that assumption, frk215, you are expected to do so in this case. The authors of the LSAT are pretty good about keeping outside knowledge out of the equation, but they do expect us to have certain basic knowledge of how the world works and to apply that to cases like this. We are supposed to know that if the sun is shining, it's daytime. We are supposed to know that living beings need food, water, air, and shelter to survive. We are supposed to understand certain basic facts about predator/prey relations and the nature/nurture debate. And they have determined that a basic understanding of supply and demand is part of that knowledge base that they consider to be fair game to test us on. And that happens to be one of their favorite themes to test in Resolve the Paradox questions! In fact, it was discussed in some detail in a recent podcast episode, found here:
https://blog.powerscore.com/lsat/lsat-p ... questions/
This answer choice falls into the general category of "something outside of what we were told occurred to cause this unusual situation to arise." It's a lot like the Foamy Soda question Dave talks about in that podcast, where causes beyond those discussed (a price reduction in that case) impacted the outcome in an unexpected way.
Be on the lookout for answers that discuss broader economic factors, weather and environmental factors, and issues related to data analysis and collection. Those are the source of many good Resolve answers!
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
Follow me on Twitter at https://twitter.com/LSATadam