已知某 MySQL 数据库中，有表及其字段如下： Employee（员工）表，字段：ID（标识，主键）、Name（姓名）、DepartmentID（班级标识，外键） Department（部门）表，字段：ID（标识，主键）、Name（名称） 要查询各部门人数（包括空部门），可以使用的查询语句是：

A.SELECT Department.Name， COUNT(Employee.ID) '班级人数' FROM Department RIGHT JOIN Employee WHERE Department.ID = Employee.DepartmentID GROUP BY Department.Name， Employee.DepartmentID

B.SELECT Department.Name， COUNT(Employee.ID) '班级人数' FROM Department RIGHT JOIN Employee ON Department.ID = Employee.DepartmentID GROUP BY Department.Name， Employee.DepartmentID

C.SELECT Department.Name， COUNT(Employee.ID) '班级人数' FROM Department LEFT JOIN Employee WHERE Department.ID = Employee.DepartmentID GROUP BY Department.Name， Employee.DepartmentID

D.SELECT Department.Name， COUNT(Employee.ID) '班级人数' FROM Department LEFT JOIN Employee ON Department.ID = Employee.DepartmentID GROUP BY Department.Name， Employee.DepartmentID

正确答案：D