针对学生选课数据库S_T，以下（ ）操作可以统计出每位学生所选课程的最高分和最低分。 A、select sno, max(grade), min(grade) from sc B、select sno, avg(grade), sum(grade) from sc group by sno C、select sno, max(grade), min(grade) from sc group by sno D、select sno, max(grade), min(grade) from sc order by sno