A、Because they cant afford to. B、Because they think small houses are more comfortable to live in. C、Because big houses are usual

In the United States, many people once lived in large, two and three story homes. Today, many people would like to live in such houses but most people can’t. (16) They don’t have enough money to buy them or even to make the first payment. So, many people rent from month to month. But some Americans really want to live in a house of their own. So they build their own home. (17) They buy a house that is situated in an area where houses are cheaper. It is better to reside in a bad part of town, they think, than not to live in a house at all. Or they buy an old house and redesign it. Then they decorate it with old style furniture. Sometimes they can make an old house look more beautiful than a new one. Usually, it is not difficult for people to find an old home to buy. (18) Many older people decide that they don’t need a big home after their children leave. So they sell their house and move into a comfortable apartment. But when people move into a house, they sometimes have problems. (19) Home owners have to do their own maintenance. For example, if the roof leaks, one can not ask the landlord to fix it. On the other hand, people can redesign their homes in any way they want without having to be afraid of being thrown out by the landlord.
Questions 16 to 19 are based on the passage you have just heard.
16. Why don’t many Americans live in large two and three story houses?
17. Where do these Americans tend to live?
18. Why is it easy to find old houses for sale?
19. What problem will people have after they buy a house?