To which group does the department with the least amount of workers belong to? Indicate the name of the department as well.
least amount of workers refers to MIN(count(DepartmentID));
SELECT T2.GroupName FROM EmployeeDepartmentHistory AS T1 INNER JOIN Department AS T2 ON T1.DepartmentID = T2.DepartmentID GROUP BY T2.GroupName ORDER BY COUNT(T1.BusinessEntityID) LIMIT 1