Which two tasks can be performed on an external table? (Choose two.) 

Answer options:

A. partitioning the table
B. creating an invisible index
C. updating the table by using an update statement
D. creating a public synonym
E. creating a view

DE

http://docs.oracle.com/cd/B28359_01/server.111/b28310/tables013.htm#ADMIN01507 You can, for example select, join, or sort external table data. You can also create views and synonyms for external tables. However, no DML operations (UPDATE, INSERT, or DELETE) are possible, and no indexes can be created, on external tables.