The conclusion of the argument is: "you should instead use praise and verbal correction to train your dog."
Why? We know that treat training consists of rewarding dogs with edible treats whenever they respond appropriately to commands. We know that a majority of dogs learn quickly what they need to do to receive the treat--so, treat training is considered to be an effective training method. But, most dogs that have been trained with treats will not obey commands unless they are shown a treat, and you cannot always have treats on hand.
So, ultimately our argument is saying since dogs who are treat trained will only obey commands when they see a treat and since one cannot always have a treat with them, this method of dog training should not be used, and instead people should train their dogs with praise and verbal correction to train their dog.
Thus, answer choice (D) puts forth the exact principle described above: "A dog should be trained to respond to a stimulus that its owner can supply in all situations."
Since an owner cannot supply treats at all times, treat training should not be the method that dog owners should use.
Hope that helps! Please let us know if you have any other questions.
