Why does performance degrade when many UPDATE, INSERT or DELETE statements are issued on a table that has an associated bitmap index?

Why does performance degrade when many UPDATE, INSERT or DELETE statements are
issued on a table that has an associated bitmap index?

A.
The DML operations re-create the bitmap index blocks

B.
Additional time is taken to remove NULL values from the bitmap index after a DML
operation

C.
The bitmap index is rebuilt automatically after a DML operation

D.
The smallest amount of a bitmap that can be locked is a bitmap segment

Explanation: