假设之前创建的KC表没有设置外键级联策略，现在通过设置触发器，实现在KC表中删除课程信息时，可自动删除该课程在xs_kc表中的学生选课信息。补全下列创建触发器的语句为（ ）。Create trigger trigger_del(　　)on(　　)for each row　　(　　)
选项：

A:Create trigger trigger_del after delete on xs_kc for each rowDelete from kc where xs_kc.kno=old.kno;;
B:Create trigger trigger_del after delete on kc for each rowDelete from xs_kc where xs_kc.kno=new.kno;;
C:Create trigger trigger_del after delete on xs_kc for each rowDelete from kc where xs_kc.kno=new.kno;;
D:Create trigger trigger_del after delete on kc for each rowDelete from xs_kc where xs_kc.kno=old.kno;