对于student学生表（sno,sname,sex,sage,sdept）以及选课表sc(sno,cno,grade)，查询刘佳同学选了哪些课，其相关嵌套查询的SQL语句是？（ ） A. select cno from sc where exists(select *From student Where student.sno=sc.sno and sname=’刘佳’); B. select cno from sc where (select *From student Where student.sno=sc.sno and sname=’刘佳’); C. select cno from sc where exists,select *From student Where student.sno=sc.sno and sname=’刘佳’; D. select cno from sc where in(select *From student Where student.sno=sc.sno and sname=’刘佳’);