While planning to manage more than one database in your system， you perform the following activities： 
1. Organize different categories of files into independent subdirectories. 
2. Use consistent naming convention for database files. 
3. Separate administrative information pertaining to each database. 
Which option corresponds to the type of activities performed by you？（）

A.Views can be created as read only.
B.Views are data segments like tables.
C.Views can be created on the basis of more than one table.
D.Data manipulation language （DML） operations cannot be performed on views.

A.control file
B.password file
C.listener controller file
D.control file and password file

A.A role can be granted to itself.
B.Roles are owned by the SYS user.
C.Roles can be granted to other roles.
D.A role cannot be assigned external authentication.
E.A role can contain both system and object privileges.