Answer:
Option A. "Backyard breeders and puppy mills are the leading causes of pet overpopulation, homeless dogs, and needless euthanasia of hundreds of dogs each day." The following statement is the best counterargument this claim should address:
Responsible dog owners who want a purebred dog should be able to purchase one from a breeder.
Step-by-step explanation:
Option A is the best possible counterclaim for the main claim that states that breeders and puppy mills are the leading cause for many negative aspects of dog's population nowadays. If there would not be breeders or puppy mills, then people who are only interest in buying a purebred dog would have no place to go to. When writing an argument, the author presents a claim, in this case the first statement, and then presents a counterclaim, which is an argument that opposes or challenges the argument the claim defends. This opens up the debate and the author's stance on the topic being discussed.