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