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(CJ)。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,CJ FROM SC WHERE CH='3'ORDER BY CJ DESC

B．SELECT XH,CJ FROM SC WHERE CH='3'ORDER BY CJ ASC

C．SELECT XH,CJ FROM SC WHERE CH='3'GROUP BY CJ DESC

D．SELECT XH,CJ FROM SC WHERE CH='3'GROUP BY CJ ASC