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, CJFROM SC WHERE CH=′3′ORDER BY CJDESC
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, CJFROM SC WHERE CH=′3′GROUP BY CJ ASC