单选题 Microsoft founder Bill Gates has ______ about being a parent, stating that 13 is an appropriate age for a child's first cell phone.
A. opened up B. taken up C. put up D. held up

【正确答案】 A
【答案解析】[解析] 句意是：微软创始人比尔·盖茨坦言为父之道，言明给孩子买第一个手机的适宜年龄是13岁。open up“直率、坦诚地说”；take up“开始从事，占用”；put up“提出”；hold up“举起……展示”。因此本题选A。