Ok, to start, this is an Evaluate the Conclusion question type. The correct answer will be something that helps us to determine whether the conclusion is valid. It does not necessarily make the conclusion valid. Rather, if we knew the info (in the correct answer), then that would be helpful in determining whether the conclusion is or is not valid.

M: dog owners think they can train unruly dogs
but many dogs can be trained only by professionals
we need to protect public safety (assumption: there is currently a public safety problem due to dogs - the argument says only that the dogs are "unruly" but that could mean barking at 5 in the morning, not necessarily public safety problems)
one of two things will help us to do that:
1) licenses for dog owners
2) no dog ownership allowed

The conclusion is: IF we either have licenses for dog owners or ban dogs entirely, THEN public safety will be protected.

This assumes not only that the plan will work as stated, but also that there is currently a dog-based public safety problem. If that problem doesn't exist, then nothing we do with respect to dogs is going to protect public safety - because dogs aren't the problem in the first place. Let's break it down a bit further for each case:

If there is a dog-based public safety problem, then is it the case that licenses for the dog owners will fix that problem? There are two big questions here - whether there's a dog problem in the first place and whether licenses for owners will fix the problem.

If there is a dog-based public safety problem, then it's easy to see how "no dogs allowed" would fix that problem. So the question for #2 is really whether there is a dog-based public safety problem in the first place.

Let's examine the answers and see whether they address either of these questions (we don't need to address both - addressing one is sufficient).

A) doesn't address either question above
B) addresses the question of whether there's a problem in the first place
C) SEEMS to address the question about licenses, except here's the problem. If we know the standards for a driver's license, does that help us to know whether "comparable" dog licenses for owners will fix the public safety problem? Comparable doesn't mean "exactly the same" - it just means "similar but adapted for a different situation." So knowing the driver's requirements doesn't tell us exactly what the dog license requirements would be. If we don't know what the dog license requirements would be, can we say whether such licenses will fix the problem?
D) doesn't address either question
E) doesn't address either question

By the way, this is a 700-800 question largely because of answer choice C - it's so very tempting. But it doesn't quite get us there.