在“学生选课”数据库中的两个关系如下：
S(SNO，SNAME，SEX，AGE)，SC(SNO，CNO，GRADE)
则与SQL命令SELECT sname FROM s WHERE sno IN (SELECT sno FROM sc WHERE grade＜60)等价的关系代数表达式是______。

_____ all the students in this class have in common is _____ they have a high object in life .[ ]

A. That ; that

B. What ; that

C. What ; whether

D. That ; what