Why does performance degrade when many UPDATE， INSERT， or DELETE statements are issued on a tablethat has an associated Bitmap index（）

• A、The DML operations re-create the Bitmap index blocks.
• B、The Bitmap index is rebuilt automatically after a DML operation.
• C、The smallest amount of a bitmap that can be locked is a bitmap segment.
• D、Additional time is taken to remove NULL values from the Bitmap index after a DML operation.