HOW MANY ROWS ARE RETURNED BY THE FOLLOWING QUERY

7. How many rows are returned by the following query?SELECT SUM(SALARY), DEPARTMENT_ID FROM EMPLOYEESGROUP BY DEPARTMENT_ID;Assume there are 11 non-null and 1 null unique DEPARTMENT_ID values. All records have a non-null SALARY value. (Choose the best answer.) A. 12 B. 11 C. NULL D. None of the above