dialogue: M: Hello, Mary. How are you today? I heard you weren't well last week. W: I'm much better now. Thank you. M: What was the matter? Nothing serious I hope. W: Oh, no. I had a bad cold and had to stay in bed for two days. M: I'm glad you're better. Anyway, I hope it was the last cold of winter and not the first cold of summer. What about your friend, Ann? I hear she is ill, too. W: She was ill. But she'll be all right now. I think she caught my cold. M: Everybody seems to have one now. I expect it's the sudden change of weather. One day hot and the next day cold. W: And very windy, too. That's why I'm wearing a sweater today. What do you think of it? Pretty, isn't it M: It certainly is. It must cost a lot. Where did you find it? W: Oh, I got it as a sale. It was quite cheap. M: Really! Well, Mary, I must say, it suits you very well. What a pity we men can't wear beautiful sweaters! W: Never mind. Let's go and buy one like it to send to your sister Linda in America. M: That's very kind of you, Mary. I'm really thinking of sending her a present.
question: Why have so many people caught a cold?
choice: Because of the cold weather. Because of no heating. Because of the changing weather.
answer: Because of the changing weather.