Once an old man went to see a doctor. The doctor looked him over carefully and Said, “Medicine won’t help you. You must have a good rest. Go to bed early, drink milk, walk a lot and go to the country place for a month. What’s more, you’d better smoke only One cigar(雪茄烟) a day. You smoked a lot before.”After a month the man came to the doctor again, “How are you?” said the doctor. “I’m glad to see you again. You look much younger.” “Oh, doctor! I feel quite well now,” said the man “I had a good rest. I went to bed early, drank a lot of milk and walked a lot. Your advice certainly helped me, but that you told me to smoke one cigar a day almost killed me first.”The doctor told the man ______.
选项：

A: to go to bed early
B: to drink milk
C: to walk a lot
D: all above