下列各组数中，是勾股数的是（　　）

根据短文理解, 从A、B、C、D四个选项中选择最佳答案填空。

    Mr. Brown lived in a small town. One day he  1 a long journey. It was very late when he was going home.  2 he found that a man 3behind him. Mr. Brown went faster, and the man walked faster too.  4Mr. Brown walked slowly and the man walked slowly 5  .

    Now they were coming near a garden. Quickly, Mr. Brown ran6  it. He tried to get away from the man in this way, but he failed. He was very afraid. He rushed and the man rushed after him. Then Mr. Brown stopped. "Excuse me, "he said, "what do you want 7?"

    " 8 , sir, "answered the man, "You see, I have to  9 Mrs. King a bag and I asked the man at the station. He told me, "go right after that man. He lives in the house just next to  10 . "

元世祖忽必烈为了有效的统治全国，建立了（    ）