Possible answers:
a). Because they are more useful.;
b). Because they are more interesting.;
c). Because they are better.;
d). Because they are cheaper.;
Q: Read the following article and answer the question. Article: Frank is my friend. His family is rich. His parents always give him lots of pocket money. But Frank thinks his parents work very hard and it's not easy for them, so he always tries his best to save money. He has some good ways to do it. Frank likes reading. He has lots of books. He tells me he often buys books online, because they're cheaper. And when he has free time, he often goes to bookstores or libraries to do some reading. Frank has a bike. He usually goes to school by bike instead of taking a bus. Sometimes when it rains or snows, he walks. These two ways help Frank keep healthy and save some money. Frank brings a bottle of water to school every day. When other students drink juice, he enjoys his water. He thinks water is the cheapest but the best drink. Some students think Frank is mean. But I don't think so. I think he is right. What do you think of him? Question: Why does always buy books online? Answer:
A:
d).