在学生选课表(SC) 中，查询选修了3号课程的学生的学号(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 GD DESC
B．SELECT XH，GD FROM SC WHERE CH＝“3”ORDER BY GD ASC
C．SELECT XH，GD FROM SC WHERE CH＝“3”GROUP BY GD DESC
D．SELECT XH，GD FROM SC WHERE CH＝“3”GROUP BY GD ASC