The CUSTOMERS table has these columns: CUSTOMER_ID NUMBER(4) NOT NULL CUSTOMER_NAME VARCHAR2(100) NOT NULL STREET_ADDRESS VARCHAR2(150) CITY_ADDRESS VARCHAR2(50) STATE_ADDRESS VARCHAR2(50) PROVINCE_ADDRESS VARCHAR2(50) COUNTRY_ADDRESS VARCHAR2(50) POSTAL_CODE VARCHAR2(12) CUSTOMER_PHONE VARCHAR2(20) Which statement finds the rows in the CUSTOMERS table that do not have a postal code? （）

A. SELECT customer_id, customer_name FROM customers WHERE postal_code CONTAINS NULL;
B. SELECT customer_id, customer_name FROM customers WHER postal_code = ' ___________';
C. SELECT customer_id, customer_name FROM customers WHERE postal _ code IS NULL;
D. SELECT customer_id, customer_name FROM customers WHERE postal code IS NVL;
E. SELECT customer_id, customer_name FROM customers WHERE postal_code = NULL