Submitted by majorgeneraldave on Aug 14 2013
The thing I like about this question (it's a Necessary Assumption question, for those of you keeping score at home) is the clear instance of what I refer to as a False Choice flaw.
By my count, this is the fourth-most-common error in reasoning on the test (your count will vary a bit depending on how you classify things). The False Choice is that hot mess that happens when you try to argue by enumeration. Like this: