A professor of business placed a case-study assignment for her class o

This question asks us which of the answer choices most strengthens the argument. It is possible that both (A) and (B) strengthen the argument but one of them will strengthen the argument more than the other.

The author argues that books delivered via computer will not make printed books obsolete. The evidence in support of this conclusion is that 50 out of 70 students printed an assignment rather than reading it on a screen.

Let's take a look at the answer choices to see why (B) is a better answer in this question:

Students acting similarly in other classes tells us that the professor's class is not an isolated case. However, there are a couple of reasons (A) is not as effective in strengthening the argument as it first appears:

• We don't know how big these other classes are. Several other classes of 5 students would not be a big addition to our sample size and wouldn't strengthen the argument much.
• We don't know how many several students are and we don't know how big the other classes are -- several students could be a handful of students from a class of hundreds. In this scenario where only a small proportion of a class is printing their assignments, (A) WEAKENS the argument.
• The students are printing their assignments, not books, perhaps because it is easier to make notes on a printed assignment than on one on a screen. It's not clear that students printing assignments can tell us much about whether people prefer to read books on screen or on paper.

It's true that having more classes where students print their assignments rather than read them on-screen could strengthen the argument, but there are a number of issues with (A) that mean we should be suspicious of it. We might not cross it out straight away but let's take a look at (B):

There are a few things to notice here:

• Studies consistently show -- this suggests the observation that follows has been repeated over multiple studies
• most computer users -- this is a very large group of people to study. We can be confident that the results from these studies can tell us something about the behavior of the population as a whole.
• will print reading material that is more than a few pages in length -- our large sample of the population will print whatever it is they're reading if it's more than a few pages long. This could refer to any type of reading material but particularly books which tend to be much more than a few pages long

Be careful with what that last part of (B) says -- it is not limiting the argument to things that are only a few pages long, it is talking about anything longer than a few pages.

(B) suggests that printing reading material, rather than reading it on a screen, is the method that lots of people prefer for a wide range of reading material. (B) definitely strengthens the argument.

(A) might strengthen the argument a little but (B) does this much more effectively, so (B) is the answer to this question.

I hope that helps!