General availability of high-quality electronic scanners -

[Sage Pearce-Higgins]

You've spotted an assumption that Ron made above! He said we might think "hey, what if the printers get better?", when he meant to say "hey, what if scanners are soon able to replicate smaller dots?". However, his assumption is a good one: scanners and printers that can reproduce more accurate detail would generally be considered better.

[NithinN389]

I believe a 'questionable assumption' is an assumption that will not support the argument. So in that case, Option D and E are good assumptions, which strengthens the argument. Options A and B are irrelevant. Option C is a questionable assumption. If Option C is assumed to be true, the bank will not be able to distinguish between a counterfeit check and a real check because they both appear the same to the naked eye. So the answer is Option C

[Sage Pearce-Higgins]

You believe wrong. This question is simply trying to confuse you by using the wording 'questionable assumption'. That's still an assumption, and we need to stick to the basics of an assumption. That is: an unstated premise that the argument needs in order to work. I get my course students to make a flashcard for this important definition. Assumptions always strengthen arguments (if they're true). And we can attack an argument by showing one of its assumptions to be false. Confusing? Here's an example of an argument that makes an assumption:

Billy likes cycling, because all girls like cycling.

You're probably thinking at this point "Wait a second, is Billy a girl? How do I know that?". Sure, the argument is assuming that Billy is a girl. Now think, what does that mean? Well, the argument needs Billy to be a girl in order for it to work. If Billy turns out to be a boy, then the argument falls apart. So, the assumption "Billy is a girl" definitely strengthens the argument, but, at the same time, we don't know if it's true.

Apply this logic to answer C, and you'll find out that it's not actually an assumption. Answer E, however, fits the definition of assumption given above. It is also somewhat questionable, given that technology improves. However, the issue of questionability is not so important.

I recommend that you re-read the chapter on Assumptions in the CR strategy guide.