单选--Is this Mr.White`s office,Mary?

单选--Is this Mr.White`s office,Mary? --Is this Mr.white`s office,Mary?为什么选C不选A hello'this is mary.hello this mr white peter's father. Mary:hello,this is Mary.Mr white :hello,this Mr white peter' 2.--Is this Mr Smith's office? Mary's father is Mr Green.Mary's husband is Mr White.we can -"Excuse me,is this Mr.Brown's office?" "Excuse me,is this Mr.Robinson's office?" 英语8.-Excuse me, is this Mr Brown’s office? Excuse me,Is this Mr Greeen's office?I'm sorry,but Mr Green (At Mr.White's office in a middle school) 选择：This is ________ father ,Mr White.