单选题]针对学生表（student(sno,sname,ssex,sage,sdept)），其中sno为学号，sname为姓名，ssex为性别，sage为年龄，sdept为系别。查询学生的姓名sname，系别sdept和年龄sage，显示时按系别升序排列，系别相同的再按年龄降序排列，以下哪条语句合适（ ）？
选项：

A:select sname, sdept, sage from student order by sdept, sage desc
B:select * from student order by sdept, sage
C:select * from student order by sdept desc, sage
D:select sname, sdept, sage from student order by sdept desc, sage