which columns would an index be automatically created when you execute the above SQL statement?

Examine the SQL statement that creates ORDERS table:
CREATE TABLE orders
(SER_NO NUMBER UNIQUE,
ORDER_ID NUMBER,
ORDER_DATE DATE NOT NULL,
STATUS VARCHAR2(10)

CHECK (status IN (‘CREDIT’, ‘CASH’)),
PROD_ID NUMBER
REFERENCES PRODUCTS(PRODUCT_ID),
ORD_TOTAL NUMBER,
PRIMARY KEY (order_id, order_date));
For which columns would an index be automatically created when you execute the above SQL
statement? (Choose two.)

A.
ORDER_ID

B.
SER_NO

C.
PROD_ID

D.
ORD_TOTAL

E.
composite index on ORDER_ID and ORDER_DATE

F.
STATUS

Explanation:

: Index exist for UNIQUE and PRIMARY KEY constraints
Incorrect answer :
* ORDER_ID is neither UNIQUE nor PRIMARY KEY
* STATUS is neither UNIQUE nor PRIMARY KEY
* PROD_ID is neither UNIQUE nor PRIMARY KEY
* ORD_TOTAL is neither UNIQUE nor PRIMARY KEY
Refer : Introduction to Oracle9i : SQL, Oracle University Study Guide, 10-15