Examine the SQL statements that creates ORDERS table:<br /> <img src="https://nimg.ppkao.com/2018-08/yiyu/201808011530357709.jpg?sign=2f110581a01f08a61042ae405cac2a73&t=62d38610" /><br /> For which columns would an index be automatically created when you execute the above SQL statement? ()
A、SER_NO
B、ORDER_ID
C、STATUS
D、PROD_ID
E、ORD_TOTAL
F、Composite index on ORDER_ID and ORDER_DATE