与查询Select student.* from student,grade Where student.sno=grade.sno and grade.score>90等价的语句是( )。
A.
Select * from student Where exists (select sno from grade where score>90)
B.
Select * from student Where sno exists (select sno from grade where score>90)
C.
Select student.* from student,grade Where grade.score>90
D.
Select * from student Where sno in (select sno from grade where score>90)