Write the next sentence in the following story.

How to diagnose urinary tract disease in senior dogs
Notice if your dog has trouble urinating.
One of the most common symptoms of urinary tract disease is an inability to urinate. Signs of urinary tract disease also include straining to urinate, urinating frequently or only urinating in small amounts, as well as crying when urinating.

Select from:
(A). If you are worried that your dog is under-urinating, go to a veterinarian or a household health clinic to make an appointment. Look out for your dog over six months old.
(B). This change commonly develops as your dog ages. Notice any difficulty taking urinary drug or using prescription medications.
(C). If your dog does urinate, check their urinate for any blood. You should also note if their urine appears cloudy, as this could be a sign of an infection.
(D). Get a prescription for prescription antidiarrheal medications. If you find that your senior dog urinates heavily and unregularly, talk to your vet about giving your dog antidiarrheal medications.. The answer should be
(C).