When trying to find the conclusion, we want to see what the author is trying to prove. Here, the author is trying to prove that pit bull is one of the category of label by job, rather than a breed of dog. That is, a pit bull is more like a police dog than a poodle.
To support this point the author illustrates the difference between the two by telling us that you cannot figure out which dog is a police dog by appearance alone. Since pit bulls are like police dogs, we therefore can say that the autgormwouldmactuallymdisagree with b.