【单选题】学生关系模式tb_student包含学号sno、学生姓名sname、性别sex、年龄age、所在院系dept等字段,要求查询各个院系的男生人数、女生人数,下列查询语句中正确的是
A.
SELECT dept, sex, COUNT(*) FROM tb_student GROUP BY dept, sex;
B.
SELECT sex, COUNT(*) FROM tb_student GROUP BY sex;
C.
SELECT dept, COUNT(*) FROM tb_student GROUP BY dept;
D.
SELECT dept, sex,SUM(*) FROM tb_student GROUP BY dept, sex;