OG Problem #57

thp510 wrote:I was wondering if anyone can provide an explanation on why my reasoning is false?

Q57: If the county continues to collect residential trash at current levels, landfills will soon be overflowing and parkland will need to be used in order to create more space. Charging each household a fee for each pound of trash it puts out for collection will induce residents to reduce the amount of trash they create; this charge will therefore protect the remaining county parkland.
WHICH OF THE FOLLOWING IS AN ASSUMPTION MADE IN DRAWING THE CONCLUSION ABOVE?

A) Residents will reduce the amount of trash they put out for collection by reducing the number of products they buy.
B) The collection fee will not significantly affect the purchasing power of most residents, even if their households do not reduce the amount of trash they put out.
C) The collection fee will not induce residents to dump their trash in the parklands illegally.
D) The beauty of the county parkland is an important issue for most of the county's residents.
E) Landfills outside the county's borders could be used as dumping sites for the county's trash.

I choose A. Here's why.
Conl: Charge will protect the remaining county parkland.
premise 1: Current level cont, landfills will overflow. Parkland will be needed for space.
premise 2: Charging ea. HH a fee for each lb of trash it puts out for collection will induce residents to reduce the amount of trash they create.

Premise 1 + Premise 2 = Concl. Therefore, this sounds like "feasibility of premise" type assumption problem. Doesn't [spoiler](A)[/spoiler] explain premise 2? The official ANS is C, however, I initially crossed it off since I thought it sounded Out of Scope (illegal dumping?). Is Choice C just a better answer than A?

Thanks for the help. [/spoiler]

Geva@MasterGMAT wrote:This question represents the harder subclass of assumption questions: the ones where the assumption is not just a link between the premises and the conclusion, but rather a necessary step: the position is that you CANNOT reach the conlcusion WITHOUT assuming C. The question you need to ask yourself when finishing the argument is "what must the author assume to reach his conclusion? If the author thinks that the fine will protect the parklands, he or she are assuming that the fine will achieve its goal of reducing trash. They must also assume that there is no harmful side effect to imposing the fine - that there's nothing stopping the fine from achieving its goal of reducing the amount of trash"

With this in mind, C suddenly makes perfect sense. The question is difficult precisely because it is very easy to label C as "out of scope" and eliminate it if you don't think about what the right answer should do before you go to the answer choices.