查询所有的男性学生姓名和年龄，按照年龄降序排列，可以使用的查询语句是：（ ）
A. SELECT Sname, Sage FROM Student WHERE Ssex = '男' ORDER BY Sage ASC;
B. SELECT Sname, Sage FROM Student WHERE Ssex = '男' ORDER BY Sage DESC;
C. SELECT Sname, Sage FROM Student WHERE Ssex = '男' ORDER BY Sage;
D. SELECT Sname, Sage FROM Student ORDER BY Sage WHERE Ssex = '男';
查询选修了数学课（课程号为2）的学生人数，可以使用的查询语句是：
A. SELECT MAX(*) FROM SC WHERE Cno = 2;
B. SELECT AVG(Sno) FROM SC WHERE Cno = 2;
C. SELECT COUNT(*) FROM SC WHERE Cno = 2;
D. SELECT COUNT(Sname) FROM SC WHERE Cno = 2;
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