题目内容：
根据以下材料，回答题。
Which of the following statements is true?
A．More than a third of brothers attack sisters in American families.
B．Almost four percent of husbands are seriously beaten by their wives.
C．Six out of one hundred couples experience severe domestic violence.
D．Six percent of American couples have some kind of domestic violence.
参考答案：
答案解析：