A、Because it is less likely to run away. B、Because it is less likely to be too shy with other dogs. C、Because it’s easier for it

Most people have had a dog or wanted one as their companion at some time in their lives.]If you are thinking of buying a dog, however, you should first decide what sort of companion you need and whether the dog is likely to be happy in the surroundings you can provide. Specialist advice is available to help you choose the most suitable breed of dog. But in part, the decision depends on common sense. Most breeds were originally developed to perform specific tasks. So, if you want a dog to protect you or your house, for example, you should choose a breed that has the right size and characteristics. You must also be ready to devote a good deal of time to train the dog when it is young and give it the exercise it needs throughout its life, unless you live in the country and can let it run freely. Dogs are demanding pets. Whereas cats identify with the house and so are content if their place there is secure, a dog identifies with its master and consequently wants him to show proof of his affection. The best time to buy a baby dog is when it’s between 6 and 8 weeks old so that it can transfer its affection from its mother to its master. If baby dogs have not established a relationship with the human being until they are over three months old, their strong relationship will always be with dogs. They are likely to be too shy when they are brought out into the world to become good pets.
Questions 19 to 22 are based on the passage you have just heard.
20. What is mentioned as a consideration in buying a dog?
21. In what way is a dog said to be more demanding than a cat?
22. Why is it advised to buy a baby dog under three months old?