Definition: 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". 
Input: [header] How to keep your mature cat healthy [title] Be sure your cat's fur is healthy and stays that way. [step] The quality of your cat's coat will depend on her diet. As your cat gets older the quality of her digestive system becomes less efficient and the nutrients are not absorbed so easily. <sep> (A) [substeps] Get your cat started grooming herself, paying attention to her hair and body. Not only does she need to be perfumed or bathed every day with shampoo, but her environment is also important. (B) When hair coat becomes ragged and thin it's a sign that your cat is unwell and needs to see the vet. She'll be tested for hyperthyroidism which is the most common hormone abnormality in cats, and sometimes only responds to a prescription diet. (C) The main thing that causes problems is her undercoat. This is where the coat loss happens and will prevent hairballs. (D) [substeps] Senior cats should be brushed frequently and trim around the face and around the eyes to remove matted fur and promote healthy shedding. Keep your young cat dry, and if possible bathe him every day.
Output:
B