On your Oracle Database, you issue the following commands to create indexes: SQL > CREATE INDEX oe.ord_customer_ix1 ON oe.orders (customer_id, sales_rep_id) INVISIBLE; SQL> CREATE BITMAP INDEX oe.ord_customer_ix2 ON oe.orders (customer_id, sales_rep_id); Which two statements are true?（）
A. Only the ORD_CUSTOMER_IX1 index created.
Both the indexes are updated when a row is inserted, updated, or deleted in the ORDERS table.
C. Both the indexes are created: however, only ORD_CUSTOMERS_IX1 is used by the optimizer for queries on the ORDERS table.
D. The ORD_CUSTOMER_IX1 index is not used by the optimizer even when the OPTIMIZER_USE_INVISIBLE_INDEXES parameters is set to true.
E. Both the indexes are created and used by the optimizer for queries on the ORDERS table.
F. Both the indexes are created: however, only ORD_CUSTOMERS_IX2 is used by the optimizer for queries on the ORDERS table.
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