Which two methods can you use to get the required result?

Examine the structure of the CUSTOMERS table:
name Null Type
CUSTNO NOT NULL NUMBER(3)
CUSTNAME NOT NULL VARCHAR2(25)
CUSTADDRESS VARCHAR2(35)
CUST_CREDIT_LIMIT NUMBER(5)
CUSTNO is the PRIMARY KEY in the table. You want to find out if any customers’ details have been
entered more than once using different CUSTNO, by listing all the duplicate names.
Which two methods can you use to get the required result? (Choose two.)

A.
self-join

B.
subquery

C.
full outer-join with self-join

D.
left outer-join with self-join

E.
right outer-join with self-join