Thanks for the question! Let’s take a look at what the passage is telling us. The council chair is advocating for an alternate code that has been successfully used elsewhere, since the traditional code has certain rules that are causing problems related to public confidence and success in endeavors.
Let’s think about what happens if (C) is true. Let’s say that revision of the traditional code that they are currently using is happening, and the problematic rules will be eliminated. If just the problematic rules are being replaced, then the council won’t necessarily quibble over procedural details and appear unworthy of public confidence, which means that the council can have success in their endeavors again. If this is the case, then it’s not necessarily the case that the entire code needs to be replaced with the alternate code, which undermines the chair’s conclusion.
Hope this helps! Feel free to ask any further questions that you might have.