which columns would an index be automatically created w…

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.
SER_NO

B.
ORDER_ID

C.
STATUS

D.
PROD_ID

E.
ORD_TOTAL

F.
composite index on ORDER_ID and ORDER_DATE

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