Billy and Bobby were small boys. They were brothers, and they often fought each other. Last Saturday their mother said to them, "I'm going to cook our lunch now, go out and play in the garden......and be good." "Yes, Mum," the two boys answered, and they went out. They played in the garden for half an hour, and then Billy ran in. "Mum," he said, "Bobby's broken a window in Mrs Allen's house." Mrs Allen was one of their neighbours. "He's a bad boy," his mother said. "How did he break it?" "I threw a stone at him," Billy answered, "and he quickly moved down." Billy and Bobby were   _  .
sisters classmates not often kind to each other always kind to each other
Question: Billy and Bobby were small boys. They were brothers, and they often fought each other. Last Saturday their mother said to them, "I'm going to cook our lunch now, go out and play in the garden......and be good." "Yes, Mum," the two boys answered, and they went out. They played in the garden for half an hour, and then Billy ran in. "Mum," he said, "Bobby's broken a window in Mrs Allen's house." Mrs Allen was one of their neighbours. "He's a bad boy," his mother said. "How did he break it?" "I threw a stone at him," Billy answered, "and he quickly moved down." Billy and Bobby were   _  .
A. sisters
B. classmates
C. not often kind to each other
D. always kind to each other
Answer: