A、To show their willingness to obey. B、To show their affection for masters. C、To avoid being punished. D、To win leadership of th

Dogs are social animals and without proper training, they will behave like wild animals. They will soil your house, destroy your belongings, bark excessively, fight other dogs and even bite you. Nearly all behavior problems are perfectly normal dog activities that occur at the wrong time and place or arc directed at the wrong thing.(20)The key to preventing or treating behavior problems is learning to teach the dog to redirect its normal behaviors to outlets that are acceptable in the domestic setting.
     (20)One of the best things you can do for your dog and yourself is to obedience training. Obedience training doesn’t solve all behavior problems,(20)but it is the foundation for solving just about any problems.
    Training opens up a line of communication between you and your dog. Effective communication is necessary to instruct your dog about what you want to do.
    Training is also an easy way to establish the social rank order. When your dog obeys a simple request of "come here, sit." it is showing obedience and respect for you. It is not necessary to establish yourself as top dog or leader of the dog pack by using extreme measures. You can teach your dog its subordinate role by teaching it to show submission to you.(21)Most dogs love performing tricks for you to pleasantly accept that you arc in charge.
    Training should be fun and rewarding for you and your dog.(22)It can enrich your relationship and make your living together more enjoyable. A well-trained dog is more confident and can more safely be allowed a greater amount of freedom than an untrained animal.
Questions 20 to 22 are based on the passage you have just heard.
20. What is the primary purpose of obedience training?
21. Why do pet dogs love performing tricks for their masters?
22. What is the benefit that a master gets from obedience training of his dog?