Q:Read the following article and select the best answer. Article: Norman Cousins was a businessman from the United States who often traveled around the world on business. He enjoyed his work and traveling. Then, after returning to the United States from a busy and tiring trip to the Union of Soviet Socialist Republics( USSR),Mr. Cousins got sick. Because he had pushed his body to the limit of its strength on the trip, a chemical change began to take place inside him. The material between his bones became weak. In less than one week after his return, he could not stand. Every move that he made was painful. He was not able to sleep at night. The doctore told him that they did not know how to cure Mr. Cousins ' problem and he might never get over the illness. Mr. Cousins, however, refused to give up hope. Mr. Cousins thought that unhappy thoughts were causing bad chemical changes in his body. He did not want to take medicine to cure himself. Instead,he felt that happy thoughts or laughter might cure his illness. .' He began to experiment on himself while still in hospital by watching funny shows on television. Mr. Cousins quickly found that 10 minutes of real laughter during the day gave him two hours of pain -free sleep at night. Deciding that the doctors could not help him, Mr. Cousins left the hospital and checked into a hotel room where he could continue his experiments with laughter. For eight days,Mr. Cousins rested in the hotel room watching funny shows on television,reading funny books,and sleeping whenever he felt tired. Within three weeks,he felt well enough to take a vacation to Puerto . Rico where he began running on the beach for exercise. After a few months,Mr. Cousins returned to work. He has laughed himself back to health. Question: Why did Norman Cousins get sick? - He did not rest enough. - He traveled too much. - His body chemistry changed. - All of the above.
A:
All of the above.