下列哪个语句实现将计算机系学生各科成绩置为0？ ( 　)　
(A) update sc set grade=0 where sc.sno=student.sno and sdept=’cs’
(B) update sc set grade =0 where sno in(select sno from student where sdept=’cs’)
(C) update grade=0 from sc where sno in(select sno from student where sdept=’cs’)
(D) update grade=0 from sc where sdept=’cs’