OCP CBT Question 528

Please solve the following question.

You need to find the number of employees in each department. Which SQL statement will correctly display the `department_id` and the total count of employees for each department?

EMPLOYEES Table Sample Data (relevant columns)
EMPLOYEE_ID DEPARTMENT_ID
----------  -------------
100         90
101         90
102         90
103         60
104         60
105         60
106         60
107         60
108         100
109         100
110         NULL

SELECT department_id, COUNT(employee_id) FROM employees;

SELECT department_id, COUNT(*) FROM employees GROUP BY department_id;

SELECT department_id, COUNT(employee_id) FROM employees ORDER BY department_id;

SELECT department_id, SUM(1) FROM employees GROUP BY department_id;