In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Q: [header] How to train a service dog [title] Pick out the quietly confident dog in a litter. [step] While guide dogs are the most common service dogs, you can also train your dog to assist people with severe allergies, diabetes, limited mobility, neurological issues, etc. Figure out what kind of dog you'd be qualified to train. <sep> (A) [substeps] Keep in mind that you'll need to have a senior for the training. Senior dogs have a shorter lifespan than older dogs. (B) [substeps] Choose a dog that is responsive to touch. If you're training a dog to follow a lead, the presence of your hand in the litter's litter box serves to ensure that it is obeying the lead. (C) [substeps] Most service dogs can't perform tricks like jumping, crouching, running, gathering grains, or playing fetch. Some only have minimal training and charge a four-month period for regular training. (D) Consider hiring a trainer of you don't meet specific qualifications. You should also consider which jobs your dog's breed and personality qualify them for.
A:
D