【单选题】设有学生表S,课程表C和学生选课表SC,他们的结构如下:S(S#,SN,SEX,AGE,DEPT), C(C#,CNO),SC(S#,C#,GRADE),检索选修课程C2的学生中成绩最高的学生学号。
A.
SELECT S# FORM SC WHERE C#='C2' AND GRADE>=(SELECT GRADE FORM SC WHERE C#='C2')
B.
SELECT S# FORM SC WHERE C#='C2' AND GRADE IN(SELECT GRADE FORM SC WHERE C#='C2')
C.
SELECT S# FORM SC WHERE C#='C2' AND GRADE NOT IN(SELECT GRADE FORM SC WHERE C#='C2')
D.
SELECT S# FORM SC WHERE C#='C2' AND GRADE>=ALL(SELECT GRADE FORM SC WHERE C#='C2')