This is tempting because you might think the argument leaves the coordination problem unresolved. But the argument does furnish a way to resolve the dilemma: have the government provide the money. That's the author's entire point. The author identifies the problem (no one entity can or will fund the network alone) and proposes a solution (government funding). So (A) inaccurately describes the argument.

Whether the network could be international rather than funded by one government is beside the point. The argument is about why the government, rather than businesses or universities, should provide the money. The scope of the network (national vs. international) is a separate issue that doesn't address a weakness in the author's reasoning about who should fund it.

This might be tempting because maintenance seems like a practical concern the author ignores. But the author's argument is specifically about who should provide the money to establish the network. Who maintains the network afterward is a separate question. Even if maintenance is an important issue, leaving it unaddressed doesn't weaken the author's reasoning about why the government should fund the network's creation.

The author's reasoning is based on the inability of individual businesses or universities to fund the network, not on any claim about boosting national scientific reputation. Since the argument doesn't rely on that assumption, (D) doesn't identify a weakness.

This points out a possibility that would undermine the author's reasoning. The premises establish that no individual business or university can afford the network or wants to invest in just a piece of it. But what if multiple businesses, multiple universities, or some combination of the two joined forces? They could pool their resources to collectively purchase the machines, and they could coordinate with each other to plan the network as a whole. If that's possible, then the government might not need to be the one providing the money after all.