A.SELECTcust_last_name,cust_credit_limitFROMcustomersORDERBYcust_credit_limitDESC
B.SELECTcust_last_name,cust_credit_limitFROMcustomersORDERBYcust_credit_limit
C.SELECTcust_last_name,cust_credit_limitFROMcustomersORDERBYcust_credit_limitNULLSLAST
D.SELECTcust_last_name,cust_credit_limitFROMcustomersORDERBYcust_last_name,cust_credit_limitNULLSLAST