在学生选课表(SC)中,查询选修了3号课程(课程号CH)的学生的学号(XH)及其成绩(GD)。查询结果按分数的降序排列。实现该功能的正确SQL语句是()
A、SELECT XH,GD FROM SC WHERE CH=’3’ORDER BY GDDESC
B、SELECT XH,GD FROM SC WHERE CH=’4’ORDER BY GDASC
C、SELECT XH,GD FROM SC WHERE CH=’5’GROUP BY GDDESC
D、SELECT XH,GD FROM SC WHERE CH=’6’GROUP BY GDASC