DATABASE DESIGN PROBLEMS. READ AND ANSWER ALL PLEASE. THANKS.

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Which of the following query will result in an error? A - select dept_id, avg(salary) from employees group by dept_id; B - select avg(salary) from employees group by dept_id; C - select dept id, job_id, avg(salary) from employees group by dept _id; select dept id from employees, (select 1 from dual) t; select dept_id from employees where salary > avg(salary); F- None of the above