Examine the description of the EMPLOYEES table: (Exhibit) Which query is valid?

A. SELECT dept_id, MAX(AVG(salary)) FROM employees GROUP BY dept_id;

B. SELECT dept_id, join_date, SUM(salary) FROM employees GROUP BY dept_id, join_date;

C. SELECT dept_id, join_date, SUM(salary) FROM employees GROUP BY dept_id;

D. SELECT dept_id, AVG(MAX(salary)) FROM employees GROUP BY dept_id;