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. dditional time is taken to remove NULL values from the Bitmap index after a DML operation.