Mr. Johnson worked in a shop which sold, cleaned and repaired hearing aids. One day an old gentleman entered and put one down in front of him without saying a word."What’s the matter with it" Mr. Johnson asked. The man did not answer. Of course Mr. Johnson thought that the man must be deaf and that his hearing aid must be faulty, so he said again, more loudly, "What’s wrong with your hearing aid, sir" Again the man said nothing, so Mr. Johnson shouted his question again as loudly as he could.The man then took a pen and a piece of paper and wrote: "It isn’t necessary to shout when you’re speaking to me. My ears are as good as yours. This hearing aid is my wife’s, not mine. I’ve just had a throat operation, and my problem is not that I can’t hear, but that I can’t speak. "（）
A. To sell hearing aids B. To buy a hearing aid C. To have a look D. To repair a hearing aid