An IT director is eager to adopt POWER7 servers because of their relative performance ratings and energy efficiency， but is concerned about migrating applications which require AIX 5.3. Which of the following will address his concern？（）

• A、POWER7 servers running AIX 5.3 operate in POWER5+ mode.
• B、POWER7 servers running AIX 5.3 operate in POWER6 and POWER6+ mode.
• C、POWER7 servers running AIX 5.3 operate in POWER5 and POWER6 modes.
• D、POWER7 servers running AIX 5.3 operate in POWER6 and POWER7 modes.