(A) tells us what libraries are doing in response to increased costs, but we are concerned with the profits of publishing companies, not libraries. We thus need an answer choice that weakens the argument by highlighting publishers’ other costs or streams of revenue.

Like (A), this is discussing the budget and costs of university libraries, rather than publishing companies. We need an answer that points out some other cost or stream of revenue that outweighs the profits made from increased university library rates.

We know publishing costs have remained constant, so (C) doesn’t weaken the conclusion that publishers’ profits have increased due to increased subscription rates for university libraries. Instead, we need something that might outweigh the extra profit from those increased rates.

This shows that the effects of other streams of revenue may outweigh increased profits from university library subscriptions. Since most subscribers are individuals with unchanged rates, publishing a scholarly journal may not be much more profitable now than it was years ago.

Regardless of the frequency of publications, we know that university library subscription rates have gone up while publishing costs have not. To weaken the argument, we need to show that the extra profits from these libraries might not be enough to boost overall profits.