If cannot skateboard in the park, children will skateboard in the streets
+
Skateboarding in the streets is more dangerous than skateboarding in the park
→
Should not pass an ordinance prohibiting skateboarding in the park
So what is going on here? This is a little bit of an odd ordering because it is basically assuming a negation of the conclusion to get at the conclusion the argument concludes.
So the councillor is saying that, "if children cannot skateboard in the park, they will do something that is even more dangerous than skateboarding in the park!" Thus, the councillor is concluding from this that they shouldn't prohibit skateboarding in the park. It basically shows the disastrous consequences of prohibiting skating in the park and comparing it to the less-disasterous consequences of allowing skating in the park.
What is the principle that is behind this? The principle is that we should try to mitigate as much danger as possible. Sure, skating in the park is dangerous but it is much less dangerous than the otherwise.
(A) We get some conditional language here with the word "unless." The answer choice is saying: (~pose a danger to participants → ~not be passed). The conclusion, or the necessary condition, looks really good here! This answer choice is concluding that the ordinance should not be passed which is exactly what the argument is concluding. However, look at the sufficient condition. Do we know that the activities don't pose a danger to the town's inhabitants. Actually, we know the opposite - skateboarding does pose a danger to the town's inhabitants. Thus, this doesn't match up with our argument and we can eliminate it. This might be a correct answer if the "unless" was swapped out for an "if" but even then it doesn't really get at the main principle of the argument but rather just restates the argument in a way.
(B) Being "legally liable" doesn't come up in our argument. This is a scope issue because the principle assumed in the argument does not rest on this.
(C) Should we pass the ordinance? Should we not?! We don't know! This also has some scope issues by talking about the "level of skill" of a skateboarder.
(D) This is tempting but only because it is actually the opposite of what we need. This says that IF the activity is dangerous (and skateboarding knowingly is) THEN we should enact an ordinance. The argument is saying that we shouldn't enact an ordinance. This doesn't line up and is thus wrong.
(E) is left standing. This has everything we need and matches up perfectly to my initial thoughts of the problem. The answer choice says this:
Enactment would lead to dangers that are greater than those eliminated → Ordinances should not be enacted.
The enactment of the ordinance in the argument definitely would lead to dangers. These dangers are greater than those eliminated (which is what the councillor's reasoning rests on). Thus, ordinances shouldn't be enacted! This matches up perfectly.