Assume you are using the UNION operator to combine the results from two identical tables, CUSTOMER and CUSTOMER$\_2.$ The CUSTOMER table contains $10$ rows, while the CUSTOMER$\_2$ table contains $7$ rows. Customers Dunne and Olowski are included in the CUSTOMER table as well as in the CUSTOMER$\_2$ table. $\_\_\_\_$ records are returned when using the UNION operator.

$7$

$10$

$15$

$17$