设有学生表student，包含的属性有学号sno、学生姓名sname、性别sex、年龄age、所在专业smajor下列语句正确的是（）。

A. SELECT sno, sname FROM student ORDER BY sname Union SELECT sno, sname FROM student WHERE smajor='CS';
B. SELECT sno, sname FROM student WHERE sex=’M’ Union SELECT sno, sname, sex FROM student WHERE smajor='CS';
C. SELECT sno, sname FROM student WHERE sex='M' ORDER BY sname Union SELECT sno, sname FROM student WHERE smajor='CS';
D. SELECT sno, sname FROM student WHERE sex='M' Union SELECT sno, sname FROM student WHERE smajor ='CS' ;