Given the following query:

SELECT lastname, firstname, order#

FROM customers LEFT OUTER JOIN orders

USING (customer#)

ORDER BY customer#;

Which of the following queries returns the same results?

a. SELECT lastname, firstname, order#

FROM customers c OUTER JOIN orders o

ON c.customer# = o.customer#

ORDER BY c.customer#;

b. SELECT lastname, firstname, order#

FROM orders o RIGHT OUTER JOIN customers c

ON c.customer# = o.customer#

ORDER BY c.customer#

c. SELECT lastname, firstname, order#

FROM customers c, orders o

WHERE c.customer# = o.customer# (+)

ORDER BY c.customer#;

d. None of the above