要实现从表users中查询所有年龄大于50岁的人的信息，将查询结果按age字段降序排序，则正确的语句是（）

A.Select * from users where age>50 order by age desc
B.Select * from users where age>50 order by age asc
C.Select * from users
D.Select * from users order by age desc