A、A very large stone. B、A cow. C、A big tree. D、A sack of rice. A

Many years ago there lived a very rich man who wanted to do something for the people of his town. But he wanted to find out Whether they deserved his help.
    In the center of the main road into the town he placed a very large stone. Then he hid behind a tree and waited. Soon an old man came along with his COW.
    "Who put the stone in the center of the road?" said the old man, but he did not try to remove the stone. Instead, with some difficulty he passed around the stone and continued on his way. Another man came along and did the same thing; then another came, and another. All of them complained about the stone in the center of the road but not one of them tried to remove it. Later in the afternoon a young man came along. He saw the stone and said:
    "The night will be very dark. Some neighbor will come along later in the dark and will fall against the stone."
    The young man then began to move the stone. He pushed and pulled with all his might to remove it. How great was his surprise at last when, under the stone, he found a bag of money and a piece of paper with these words: "This money is for the first honest, man who removes this stone from the road."