A.External tables can be updated. 
B.External tables are read-only tables. 
C.Indexes can be created on external tables. 
D.Indexes cannot be created on external tables.

A.The Oracle server creates a new histogram based on existing histogram definitions for all table, column, and index statistics for the OE schema. 
B.The Oracle server creates a histogram based on data distribution regardless of how the application uses the column/s for all table, column, and index statistics for the OE schema.
C.The Oracle server creates a histogram based on data and application usage of the column/s for all table, column, and index statistics for the OE schema. 
D.The Oracle server creates a histogram based on application usage, regardless of data distribution, for all table, column, and index statistics for the OE schema.