A: Fast Incremental backups is possible with Block change tracking, which is initially introduced from version 10.2 onwards, by this tool it's very useful to reduce the RMAN incremental backup duration.
If the changes are something around 20% then in this situation BCT helps a lot.
C: Exadata Storage Server offload capability combined with RMAN block change tracking will efficiently perform large I/Os at the storage-tier level, returning only individual changed blocks for incremental backups and increasing the backup performance of the system.
Note: Level 1 backup: A level 1 backup includes only those blocks that have been changed since the "parent" backup was taken. Remember a parent backup may be either a level 0 or a level 1 backup.
Block change tracking allows indeed the highest benefit for databases where the changes are not so high, Level 0 backup: A level 0 incremental backup is physically identical to a full backup and it includes every data block in the file except empty blocks. The only difference is that the level 0 backup is recorded as an incremental backup in the RMAN repository, so it can be used as the parent for a level 1 backup.
References:
http://www.dba-oracle.com/t_rman_backup_types.htm
http://www.oracle.com/technetwork/database/availability/maa-tech-wp-sundbm-backup-11202-183503.pdf
https://www.toadworld.com/platforms/oracle/w/wiki/11124.fast-incremental-backups-active-data-guard

C: Login as root on IB switch and run,
# env_test
Example output include:
Starting FAN test:
Fan 0 not present
WARNING Fan 1 running slow rpm 5450 limit 6440
WARNING Fan 2 running slow rpm 5341 limit 6440
WARNING Fan 3 running slow rpm 5341 limit 6440
D: The showtemps command displays internal temperatures for the switch.
The following example shows how to display switch temperatures with the showtemps command.
# showtemps
Back temperature 29
Front temperature 30
SP temperature 36
Switch temperature 52, maxtemperature 56
All temperatures OK
#
References:http://myoraclediary.blogspot.se/2014/04/all-about-infiniband-switches-on- exadata.html

Explanation/Reference:
D: In-Memory Columnar Caching on cells is enabled by default when the INMEMORY_SIZE is configured.
You do not need to do anything to get this enhancement.
E: Columnar Flash Caching implements a dual format architecture in Exadata flash by automatically transforming frequently scanned Hybrid Columnar Compressed data into a pure columnar format as it is loaded into the flash cache.
Incorrect Answers:
F: Columnar Flash Caching accelerates reporting and analytic queries while maintaining excellent performance for OLTP style single row lookups.
References:
http://docs.oracle.com/cd/E80920_01/SAGUG/exadata-storage-server-monitoring.htm#SAGUG20883
http://www.oracle.com/technetwork/database/exadata/exadata-x5-8-ds-2745934.pdf