Explanation/Reference:
Explanation:
A, D: The value for the disk group COMPATIBLE.ASM attribute determines the minimum software version for an Oracle ASM instance that can use the disk group. This setting also affects the format of the data structures for the Oracle ASM metadata on the disk.
B: The value for the disk group COMPATIBLE.RDBMS attribute determines the minimum COMPATIBLE database initialization parameter setting for any database instance that is allowed to use the disk group.
Before advancing the COMPATIBLE.RDBMS attribute, ensure that the values for the COMPATIBLE initialization parameter for all of the databases that access the disk group are set to at least the value of the new setting for COMPATIBLE.RDBMS.
For example, if the COMPATIBLE initialization parameters of the databases are set to either 11.1 or 11.2, then COMPATIBLE.RDBMS can be set to any value between 10.1 and 11.1 inclusively.
Incorrect Answers:
E:
/The value for the disk group COMPATIBLE.ADVM attribute determines whether the disk group can contain Oracle ASM volumes. The value must be set to 11.2 or higher. Before setting this attribute, the COMPATIBLE.ASM value must be 11.2 or higher. Also, the Oracle ADVM volume drivers must be loaded in the supported environment.
/You can create an Oracle ASM Dynamic Volume Manager (Oracle ADVM) volume in a disk group. The volume device associated with the dynamic volume can then be used to host an Oracle ACFS file system.
The compatibility parameters COMPATIBLE.ASM and COMPATIBLE.ADVM must be set to 11.2 or higher for the disk group.
Note:
* The disk group attributes that determine compatibility are COMPATIBLE.ASM, COMPATIBLE.RDBMS.
and COMPATIBLE.ADVM. The COMPATIBLE.ASM and COMPATIBLE.RDBMS attribute settings determine the minimum Oracle Database software version numbers that a system can use for Oracle ASM and the database instance types respectively. For example, if the Oracle ASM compatibility setting is 11.2, and RDBMS compatibility is set to 11.1, then the Oracle ASM software version must be at least 11.2, and the Oracle Database client software version must be at least 11.1. The COMPATIBLE.ADVM attribute determines whether the Oracle ASM Dynamic Volume Manager feature can create a volume in a disk group.

AB:You can make individual table columns invisible. Any generic access of a
table does not show the invisible columns in the table. For example, the following
operations do not display invisible columns in the output:
*SELECT * FROM statements in SQL
*DESCRIBE commands in SQL*Plus
*%ROWTYPE attribute declarations in PL/SQL
*Describes in Oracle Call Interface (OCI)
Incorrect:
Not D:You can make invisible columns visible.
You can make a column invisible during table creation or when you add a column to a
table, and you can later alter the table to make the same column visible.
Reference:Understand Invisible Columns

Explanation
A: Variable size extents enable support for larger ASM datafiles, reduce SGA memory requirements for very large databases (A), and improve performance for file create and open operations.
C: You don't have to worry about the sizes; the ASM instance automatically allocates the appropriate extent size.
Note:
* The contents of ASM files are stored in a disk group as a set, or collection, of data extents that are stored on individual disks within disk groups. Each extent resides on an individual disk. Extents consist of one or more allocation units (AU). To accommodate increasingly larger files, ASM uses variable size extents.
* The size of the extent map that defines a file can be smaller by a factor of 8 and 64 depending on the file size. The initial extent size is equal to the allocation unit size and it increases by a factor of 8 and 64 at predefined thresholds. This feature is automatic for newly created and resized datafiles when the disk group compatibility attributes are set to Oracle Release 11 or higher.