This is not a good question. And the red for should be to in my opinion.

① Getting in touch (联系) with friends is difficult after people change schools or move house. They don't know how to start the conversation (交谈) again if they don't talk with their friends for a long time. Many people want to get in touch with old friends, but they are afraid to do so.
② Psychologists (心理学家) from colleges in Canada and the UK did a study among 2,500 people. They wondered how people felt about the idea of getting in touch with old friends.
③ The study shows over ninety percent of the people don't call their old friends. 70% of them don't want to call their friends first, because they worry that their old friends won't want to hear from them or they are too busy to talk with them. Some people even think getting in touch with their old friends is as hard as talking to strange (奇怪的) people.
④ Lara Aknin, one of the psychologists, said, "Most people worry they won't have much to talk about with their old friends since they have different interests now. But in fact, these differences can be helpful for people to get close to each other. After sharing something new and interesting, they won't feel embarrassed (尴尬的) at all. Instead, they know each other better."
⑤ In fact, most of people's worries are just useless. If you do get in touch with an old friend, you will be surprised to find that he or she is also looking forward to hearing from you. So, why not pick up your phone and give your old friend a call?

( )28. Why don't some people want to call their old friends first?
A. Because they don't care about their old friends at all.
B. Because they have nothing to say to their old friends.
C. Because they don't want to bring problems for their old friends.
D. Because they are too busy to keep in touch with their old friends.