Since we already know from the premises that these signs are designed for "improved readability", it doesn't help us evaluate the argument to know what specific features of the signs — color, font, etc. — make them more readable. We know that they are somehow designed to be more readable: to decide whether or not it is a colossal waste to install these new signs, we want to know whether improved readability is enough of a benefit to outweigh the time and money used to install them. Answering this question wouldn't tell us that.

First, notice that this question talks about the cost of manufacturing the signs. The politician only mentions the cost of "installing" the signs. It's not clear that the cost of installation necessarily includes the cost of manufacturing, so it's not clear that this question would necessarily help us evaluate the politician's claim.

But even if we assume that the cost of manufacturing is included in the cost of installation, and even if we answer this question "yes", meaning the new signs are much more expensive to manufacture than the current ones were, this question still isn't very useful. It's important to see that what determines if this project is a "colossal waste" or not isn't just whether the new signs will cost more to manufacture or install than the current ones, but whether the cost of the new signs — whatever that is — is balanced out by benefits provided by the new signs. So even if the new signs are more expensive both to manufacture and to install than the current ones were, it would be hard to call this expense a "waste" if the new signs provided equivalent benefits to the city, compared to the current signs — reduced traffic, for example, or less frequent accidents. To evaluate the politican's claim, we also need to know about the benefits provided by the new signs compared to the status quo. Just knowing how the cost of the new signs compares to that of the current ones doesn't tell us anything, so this question doesn't help us.

This is important to know. If the city already replaces many signs each year in the course of ordinary maintenance, then the city is already spending time and money on swapping out signs. So it seems much less likely that putting up these new signs, even if it costs slightly more, will constitute, on net, a "colossal waste" of resources. If the city replaces few or none of its signs each year, then the city is starting a brand-new project that no one has asked for. This doesn't necessarily strengthen the politician's claim — we still don't know if the time and money involved count as a "colossal waste" — but it at least leaves it neutral. Because answering this question can help us evaluate the strength of the politician's argument, this is the correct answer.

We’re not interested in other cities. Knowing what other cities plan to do, presumably based on different budgets and different needs, tells us nothing about whether or not it is a "colossal waste" for this city to install the new signs.

Answering this question "yes" might seem to support the idea that these signs will provide some benefit. But the signs could still provide benefits even if experts weren't consulted, and to decide whether or not installing these signs is a "colossal waste," which is a statement about net result, it's not enough just to know whether or not there are benefits from these signs. We need to know how those benefits compare to the amount of time and money committed to installing the signs — and even if there are no benefits, we need to know whether the time and money used are substantial enough to count as a colossal waste. So answering this question "yes" or "no" doesn't help us evaluate the politician's claim.