A、What dogs can do. B、How to keep dogs. C、Dogs and their masters. D、Reasons for keeping dogs. D[听力原文] What is the passage mainly

If you’re in a western country, you often see people walking their dogs. It is still true that a dog is the most useful animal in the world. However the reason why one keeps the dog has changed. Once upon a time, a man met a dog and wanted it to help him in the fight against the other animals. And the dog listened to him and did what he told him to do.Later people used dogs for hunting other animals. And dogs did not eat what they got untill their masters agreed. Dogs were also used for driving sheep and guarding chickens. But now people in towns and cities do not need dogs to fight other animals any more. Of course, they keep them to frighten thieves. But the most important reason for keeping dogs is that they feel lonely in the city. For a child, a dog is his best friend when he bas no friends to play with; for a young wife, a dog is her child when she does not have her own; for old people, a dog is also a child when their real children have grown up and left. Now people do not have to use a dog, but they keep it as a friend, just like a member of the family.