The EMPLOYEES table has six indexes and DML operations are slow. Which command begins monitoring the EMPLOYEE_IDX_FK index to determine whether it has been used by an execution plan？（）

• A、ALTER TABLE employees monitor index employee_idx_fk; 
• B、ALTER INDEX employee_idx_fk monitoring on; 
• C、ALTER TABLE employees monitor all indexes; 
• D、ALTER INDEX employee_idx_fk monitoring usage;