阅读下面短文，掌握其大意，然后从各题所给的A、B、C、D四个选项中选出最佳选项。
A clever man was on his long journey with a young man. Night was coming, so they decided to find a place to stay. They searched for a long time and at last found a small old house. A1family lived in it. They gave the two visitors a warm welcome and prepared a simple2for them including fresh milk and cheese.
After the meal, the clever man asked how they made a living in such a poor place. In a low voice the husband answered, "We have a3. We sell her milk to others and keep some for4own needs-make some cheese and cream."
The next morning, the two visitors continued their5. After they walked a few miles, the clever man said to the young man, "Go back and push the sheep off the cliff (悬崖)". "Why? Without the sheep, they will have nothing. "The clever man said again, "Go back and6the sheep."
The young man was worried about the future of the family. But7he returned to the old house and did as the clever man told him.
A few years later, the young man travelled on the same road. He decided to visit the family again. To his surprise, he saw a large house with a beautiful garden there.
He knocked on the door and a well-dressed man answered it. He was the son of the family. The man let him enter the house and told him8their life changed. "You know, we had9but a sheep to keep us alive before. But she fell off the cliff and died. We had to come up with new ways of making a living. You see, we are much10than before. "At his words, the young man smiled.
B. 
C. 
D. 
E. 
F. 