设有关系模式:SC(sno,cno,grade),各属性含义依次是学号、课程号、分数。要查询分数低于60分的学生学号,正确的SQL语句是______。A) SEI,ECT sno FROM SC WH ERE grade BETWEEN O AND 60B) SELECT sno FROM SC WHERE grade<60C) SELECT sno FROM SC HAVlNG grade BETWEEN O AND 60D) SELECT sno FROM SC HAVING grade<60