Explanation

Reading the question: this argument contains a lot of introductory material and bluster. The important stuff starts with "it represents a waste of money," the conclusion. The key piece of evidence is the cost comparison: maintaining existing roads vs. building the tube. Even if that evidence is true, as we take it to be, there might be benefits to this tube idea that have not been considered within the argument. We'll take that observation and use "new benefit," a tube-positive idea, as our filter for an answer choice that weakens the argument.

Applying the filter: choice (A) is tube-negative, so it doesn't pass the filter. Choice (B) is tube-positive, but barely, and it's not a new benefit. (B) is out. (C) is a big new benefit: looks good. (D) is not much of a new benefit, since we are told the cost of maintaining the roads is negligible. (D) is out. (E) is better than the other wrong answers, but it doesn't clearly establish a benefit.

Logical proof: using the negation test, we can observe that if the new technology for the tube system had no application outside this project, then the tube project would be harder to justify. The negated (C) strengthens the argument, confirming that the non-negated (C) weakens the argument. The correct answer is (C).