Most kinds of soil contain clay, and virtually every kind of soil contains either sand or organic material, or both. ...

Jacob-R on November 14, 2018

I’m happy to help. As always, let’s start with the question stem. We are looking for an answer with flawed reasoning that is parallel to that in the passage. In order to find that, we need to understand that flawed reasoning.

The passage says:

Most soil contains clay, and almost every kind of soil contains either sand or organic material, or both.

Then there is a conclusion: There must be some kinds of soil that contains both clay and sand AND some that contains clay and organic material.

How would you describe that logical error? Isn’t it possible that even though most soil contains clay, clay is only found in the soil that has organic material, and never sand? That wouldn’t violate the premises, and is an answer contrary to the passage’s conclusion.

Answer E makes that same error. Nearly all pharmacies sell either shampoo or toothpaste or both (this is our soil/organic/both equivalent.) Most pharmacies sell cosmetics (this is our clay equivalent.) And then there is the same jump — there must be some pharmacies that sell both cosmetics and toothpaste and some that sell both cosmetics and shampoo. Again, couldn’t it be that the “most” that sell cosmetics are only the shampoo selling category? Same error!

I hope this helps. Please let us know if you have further questions.