Which two statements are true about views?

Views in Oracle have specific properties regarding how they can be used and what limitations apply to them:

A. Oracle does not allow indexing directly on views. However, a view can display data from indexed tables.

B. The WITH CHECK OPTION clause on a view prevents DML operations that would result in rows that do not satisfy the view’s filter criteria. It doesn't prevent certain rows from being updated or inserted in the underlying table through the view per se.

C. The tables (or other views) referenced in the creating query of a view must exist at the time the view is created, making this statement true.

D. Views do not require privileges to be re-granted when the view is updated; they are separate from the underlying object privileges, making this statement true.

E. The WITH CHECK OPTION clause is used to ensure that all data modifications through the view are consistent with the view's defining query, not to prevent rows from being displayed.

References:

Oracle Database SQL Language Reference, 12c Release 1 (12.1): "CREATE VIEW"

Oracle Database Concepts, 12c Release 1 (12.1): "Views"