Before a Flashback Table operation，you execute the following command：   ALTER TABLE employees ENABLE ROW MOVEMENT；   Why would you need this to be executed？（）  

• A、 Because row IDs may change during the flashback operation
• B、 Because the object number changes after the flashback operation
• C、 Because the rows are retrieved from the recycle bin during the flashback operation
• D、 Because the table is moved forward and back to a temporary during the flashback opertion