Examine the description of the EMPLOYEES table:
EMP_ID NUMBER(4) NOT NULL
LAST_NAME VARCHAR2(30) NOT NULL
FIRST_NAME VARCHAR2(30)
DEPT_ID NUMBER(2)
Which statement produces the number of different departments that have employees with last name Smith?
A. SELECT COUNT(*) FROM employees WHERE last_name=’Smith’;
B. SELECT COUNT (dept_id) FROM employees WHERE last_name=’Smith’;
C. SELECT DISTINCT(COUNT(dept_id)) FROM employees WHERE last_name=’Smith’;
D. SELECT COUNT(DISTINCT dept_id) FROM employees WHERE last_name=’Smith’;
E. SELECT UNIQUE(dept_id) FROM employees WHERE last_name=’Smith’;